Virtualisation is not new. Ask anyone with a passing familiarity with a mainframe. Given the way it has been punted lately, you'd be forgiven for thinking it is new. Virtualisation, we've been told, will save power, cut costs, reduce administration and management overheads, and do everything almost up to and including making the boss tea in the morning.

If only real life was that simple. Virtualisation can indeed save power, cut costs, reduce overheads and make life easier, but there's some fine print to consider.