THE Roxy nightclub on Hollywood's Sunset Strip loves a celebrity party. This is the place where John Belushi partied shortly before dying of an overdose, where John Lennon held his debauched "lost weekend" in 1975 and where Heidi Fleiss held her infamous 1980s soirees for Hollywood's rich and powerful. So when Paris Hilton, Amy Winehouse, John Stamos, Kelly Osbourne and Dita Von Teese showed up to dance the night away last Friday night, the doormen did not bat an eyelid.

But this was no ordinary night out for Hollywood's darlings. The guest of honour was a blue-haired, blusher-cheeked gay Cuban-American called Perez Hilton, a celebrity blogger whose scurrilous website has the power to make or break careers. Just ask the singer Mika, whose fame in America was kickstarted with the help of perezhilton. com. Or ask Neil Patrick Harris, the one-time child star of Doogie Howser MD, who was forced into a confession of his homosexuality after Hilton "outed" him on the site.

So vicious is the gossip on perezhilton. com, and so heavy is the web traffic (one day last month Hilton had 4.75 million unique viewers), that he has become a major player in Hollywood's star-making factory. It is a measure of how far he has come in two years that publicists now contact Hilton with stories about their clients. Indeed, as both the invitation list to his 29th birthday party and the growing body of web gossip about Hilton shows, he is well on the way to becoming a celebrity himself.

"Oh, I don't know about that. I definitely don't see myself like that, " says Hilton (whose real name is Mario Lavandeira), sitting outside his favourite haunt, the Coffee Bean and Tea Leaf cafe on Sunset and Fairfax. But, if he's not a celebrity himself, how did he pull such a good crowd for his birthday party?

Weren't his star guests scared he was going to post unflattering stories about them on his website?

"They came because they knew it was going to be a lot of fun, " he says. "All the people who did come are the ones who have a sense of humour and who don't take themselves too seriously. I notice Jennifer Aniston didn't show up, nor would she ever. I wouldn't have let her in, anyway."

Aniston had good reason to stay away.

Like many celebrities, she has been subjected to daily vilification on Hilton's site. She is nicknamed "Maniston", derided for her lack of talent and humour; and photographs of her are frequently daubed with unflattering body appendages in Hilton's trademark white pen. Hold on . . . does that mean Perez thinks Paris Hilton has a sense of humour?

"Paris Hilton has a great sense of humour!"

he says. "She doesn't care what people say about her . . . and, clearly, she's doing something right because people are still interested."

Perez Hilton's bias is part of his appeal. And he's happy for guests to his website to disagree violently with him . . . and even for them to abuse him personally. "I don't censor anything, " he says. But the fact remains . . . he enjoys being a friend to a group of stars.

The London celebrity gossip columnist Mr Holy Moly says it could be the site's undoing.

"I think he's pretty smart to a degree, " says the blogger. "He is clearly aiming to become a celebrity himself, which will ultimately shaft the website. You do need to be consistent.

"You can't not slag off Paris Hilton just because you now consider her a friend. She's clearly a f***ing imbecile. So, if the site is to continue, he needs to maintain his stance against the celebrities. If, however, his longterm aim is to be an X Factor judge, or have his own show, then he's going the right way about it. ."

So can Hilton, who before he started blogging worked as an actor and then a publicist, afford a grand lifestyle? "I started this blog because I thought it would be easy, " he says.

"[But] I work hard. I wake up at 5.15am and start working. I put in 17/18 hours a day, working on my website. I'm not one of these people that can go out until 3am or 4am and wake up at noon. But sometimes, sure, I enjoy some of the perks that celebrities do."

It's not all perks, though . . . Hilton is starting to suffer some of the downsides to celebrity. Recently, a chapter appeared on his Wikipedia entry stating that "Lavandeira test [sic] positive for HIV in 2004. He has kept this confidential, until now, but as a result of outing celebrities, we felt it our duty to 'out' him over his illness. Karma is a b. i. t. c. h."

The chapter has now been closed down and Hilton will neither confirm or deny its veracity, saying only that "people put stuff on sites the whole time".

The episode, though, is a reminder that Hilton has made some enemies in his twoyear blogging career. His speciality of outing male celebrities has proved contentious in Hollywood, especially as he has driven a couple of big names . . . Lance Bass, formerly a singer with N'Sync, and Neil Patrick Harris . . . on to the front pages of magazines with confessions of their homosexuality. But there are more celebrities whom Hilton is encouraging to come out, although with what evidence he does not say.

Why do it? Does he not believe that people should come out in their own time?

"I believe in reporting the truth and if I know something to be true I'm going to report it, " says Hilton. "I don't believe in discrimination. I'm going to treat everyone the same . . . gay or straight, out or not." But outing someone can drastically alter their personal and professional lives and career. Is he always 100% sure of his facts before he publishes? "Yeah I am . . . with [Neil Patrick Harris] I knew his boyfriend. So, yeah, I was sure."

There are ethical complications with Hilton's approach. For one, his high-minded ideals of treating everyone the same do not quite fit with the partiality he displays towards certain celebrities. Second, outing someone is different to showing pictures of them arriving at rehab or falling out of cabs with no knickers on.

Being gay, as Hilton knows, should not be a source of shame . . . and the act of outing brings shameful connotations. "Actually, hiding in the closet reinforces the idea that there's something shameful about being gay, " counters Peter Tatchell, the British gay rights activist and a serial "outer" himself.

"There is a moral imperative to come out if you are gay . . . to challenge ignorance and prejudice. But how and when people come out is up to them. The only exception for outing someone against their will is if they are a public figure and they are living a hypocritical or homophobic life."

So, does Tatchell support how Perez outs minor celebrities? "It depends . . . are they deliberately and ostentatiously pretending to be straight, while conducting homosexual relationships in private?" Tatchell asks. "In that case, it's in the public interest they are exposed. But this is a difficult area and it's one in which the nuances are important."

One suspects Hilton doesn't 'do' nuance and ethical considerations do not tax him. He exists, he believes, to break stories. What may be of more interest to him is the increasing interest picture agencies are taking in his use of uncredited celebrity photographs. Indeed, one agency, X17, is currently suing Hilton for damages of $7.5m for copyright infringement. Is he worried?

"They should be worried about my suit . . .

I've sued them, " he says. "They lied to the court. When they filed that lawsuit, they did not have copyright to any of the 50 pictures they are talking about. The copyright process only began after the lawsuit was filed. So I'm suing them for monetary damages."

This one case is part of a greater problem surrounding websites, the outcome of which, says Mr Holy Moly, could have "a massive impact on the way blog sites are run".

"If [Hilton] loses, " says Mr Holy Moly, "95% of all US celebrity blogs will cease to function overnight as they are predominantly picture galleries with commentary. If he wins, the paparazzi may as well just f*** off home and leave it to kids with cameraphones. Ultimately, if the picture agencies came up with a sensible web tariff based on traffic, we wouldn't be in this mess. They can't expect to charge Holy Moly or Perez the same as a blanket deal with the Mirror Group."

Anyway, says Hilton, he already has excellent relationships with some picture agencies.

"A lot of agencies actually send me their pictures, " says Hilton, "because they realise that one dude with a website who is doing it for fun is being read by four million viewers.

So having their photo on the site helps them to sell it. That's why so many of them send me their pictures . . . including people like Big Pictures in the UK."

Hilton's ambition is, he says, simple. He has never been motivated by money, he just wants as many people as possible to read the website.

However, with the possibility of his own reality television show in the pipeline, he will soon face a choice. Either he can write, or he can be written about. But Hilton does not see things so black and white: "I can dish it out, but I can also take it, " he says. "People can write what they want. That's what the website's always been about."