If James Governor is right (and I think he is) - then internal IT shops are probably doomed:

Finally it strikes me we may be about to see something entirely new in the industry. Twitter is emerging as a core lightweight Web infrastructure but unlike earlier Web companies isn’t buying and building out its own infrastructure. Twitter is a hosted architecture of participation. Unlike first web wave companies, Google as poster child, this is On Demand purchasing.

Amazon was early with their elastic computing initiative, and I'm not sure that Sun has the right target for their "data center in a box" idea - but it looks like IT infrastructure is moving away from being a local concern. Back in the early days of electricity, "everyone" bought a generator - that didn't scale well, and the entire model moved to a carrier one. I think we are starting to see the same thing in IT infrastructure, only with a lot more competition. I suspect that companies that keep their IT internal - unless their needs are very, very unique - are going to be spending a lot more money than their competitors.