It is also beginning to attract economic activity and investment from the Republic on a scale beyond Celtic Tiger property speculators travelling north to buy cheap houses and commercial property. While that's undoubtedly good news north of the border, at the moment the Republic seems to be the recipient of what is known in American investment circles as an "Irish dividend" . . . an assessment on a holding rather than a pay-out.

Aer Lingus's recent decision to move its Heathrow service from Shannon to Belfast is possibly the most high-profile example of this developing macro trend, alongside Bank of Ireland's move to relocate its hedge fund administration to Belfast over the next five years. But other significant rumblings are also starting to be heard.

Earlier this month the managing director of Co Louth's offshore Oriel Windfarm threatened to connect to the Northern electricity grid unless the government reforms its licensing policy and sweetens the pot for wind energy. And One51 chief executive Philip Lynch told his shareholders at their AGM two weeks ago that he was ready to "reach across the border" to develop Co Louth's Greenore Port . . . which is 50% owned by One51 . . . as a way of freeing up Irish Continental Group's property in Dublin Port for development.

The question that emerges therefore is whether continuing, albeit slowed, growth of the Republic's Dublin-centric economy allied with a resurgent northeast will affect other areas of the island as international and national businesses decide that the North's lower wage costs, cheaper property and sterling environment are more attractive than the eurozone Republic's lower corporate tax rate, regional development grants and skilled workforce.

The 1bn transformation of Belfast's Titanic Quarter into a new commercial and financial hub, and the continued expansion of the Northern Ireland Science Park where Microsoft and CitiGroup have established operations illustrate a confidence in the future of Northern Ireland. Aer Lingus's decision to relocate its Heathrow business route from Shannon to Belfast prompted the chambers of commerce of Ennis, Galway, Limerick and Shannon to highlight the "immense strain" western industries are under in relation to high energy and running costs and, of course, international transport infrastructure.

Commentators are therefore raising questions about the effect a true all-island economy might have on peripheral areas outside the Belfast-Dublin axis.

Opinion is mixed. Business umbrella group Ibec and its plethora of industry associations have broadly welcomed the creation of an all-island economy, as do the majority of politicians of all shades across the island whenever their local patch is not perceived to be affected.

But based on comments coming from the business community in places like Cork, Galway and Limerick, there is a hard-nosed commercial reality dawning that the reinvigoration of the economy of the north east of this island may pose threats as well as opportunities to areas outside the Pale.

Ulster Bank economist Pat McCardle believes the Irish economic landscape is based on 'cluster economics' where certain industries and their support services bunch around specific areas. Cork's concentration of pharmaceutical companies is a prime example. He says the sparsely populated west has always had to deal with this reality.

"There's a very strong gravitational pull for business to major population centres. Now there's three in terms of Cork, Dublin and Belfast in one economy. There are national economic factors at work. This has been reinforced by developments such as peace in the North and enhanced cooperation between the two governments."

Sinn Fein finance spokesman Mitchell McLoughlin has called for an all-Ireland spatial strategy to address these issues and dampen concern that areas west of the Shannon and west of the Bann do not disproportionally lose out to the east coast.

"What no one wants to see is interregional rivalry that would set people who champion regional development at each other's throats, " he said.

InterTrade Ireland, the North-South business development body set up under the Belfast Agreement, sees greater mobility across the border as benefiting the entire island of Ireland and not just the Dublin-Belfast corridor.

"It [North-South investment] is already happening both ways while 10 or 15 years ago business people didn't consider investing across the border because there was a chill factor . . . that's melting now, " said InterTrade chief executive Liam Nellin. He said policy makers should be "alive" to the issue of a Dublin-Belfast axis overpowering the regions, but added that industrial development bodies such as InterTrade, which has projects in every county of Ireland, were focused on increasing economic activity in all regions.

Historians will tell you partition never truly separated the northern and southern economies . . . they were decoupled . . . but reintegration is gathering pace. This isn't unlike the reintegration of the West and East German economies which the German Irish chamber of commerce described as a "Big Bang" example of two economies coming together.

Holger Erdmann of the German-Irish chamber believes the "softer" economic process under way in Ireland will create more sustainable opportunities for economic development, but he also warned against duplicating the experience of areas of Germany, such as Saxony, where growth far outsripped other regions when national economic horizons expanded.

"This is not too likely in Ireland, but there is a possibility that the east coast link between Dublin and Belfast might be bad for the rest of Ireland, " he said.