Last week, to a small fanfare, Microsoft formally announced the opening of its Dublin 'mega-datacentre'. In the old days, the opening of a datacentre was no big deal, of course. It was a server room built largely for internal purposes and it was essentially an expensive dull-but-necessary commodity.

The new datacentres are different. They're many times larger (this one is over 300,000 square feet), have incredible power capacity (up to 22 megawatts), are designed to serve millions of external users accessing services over the internet, and they have massive bandwidth, processing and storage capabilities. They must be highly resilient and not just available but very fast too.

Some people call them mega-datacentres, others bit factories or similar names. They are the powerhouses of internet computing, the necessary elements to enable clouds. They will undoubtedly be popping up everywhere for several years to come, typically in areas where IT giants, telecoms and communications behemoths and specialists can provide high-quality services to customers at lowest cost. You might think of these as the modern equivalent of call centres in the 1990s, out-of-town shopping precincts in the Noughties, or -- albeit on a minor note -- comparable to the building of electricity pylons, rail tracks and telegraph poles in previous times.

There is no doubt that they will underpin many areas of economic activity but in one interesting way they are different. Whereas all these previous examples would have provided a boom in employment, such is the level of automation in the mega-datacentres that they will employ only a small number of staff. The Microsoft Dublin datacentre might have cost $500m in "total investment", as Microsoft says, but how many people do you think will be employed there full-time?

Microsoft tells me the number is... between 35 and 50.