It is accepted that the big Web2.0 companies don't buy what the enterprise guys buy.

Wired has an article on how Amazon changed its server purchasing to follow Google.

Pinkham was struck by how different the machines looked — and how hot they were. Even then, Google was running its website on dirt-cheap, stripped-down servers slotted into extremely tight spaces. They didn’t even have plastic cases.

“They were clearly not your average Dell, HP, IBM servers. They were white box machines, very densely packed. They weren’t in containers. They were just blades jammed into these custom racks,” remembers Pinkham, who went on to lead the team that built the Elastic Compute Cloud and now runs a cloud software startup called Nimbula. “And I remember a lot of heat coming off them — an indication of a lot of concentrated power.”

This isn't really new to most of you, but it is nice to have a Wired article tell a story to the rest.