Via Nick Carr comes a fairly obvious insight: we tend to try solutions based on what's worked for us in the past. Google builds out racks and racks of commodity servers, and IBM? It's all about mainframes:

The Register's Ashlee Vance points to a fascinating white paper about IBM's Project Kittyhawk, an initiative aimed at the possible construction of "a global-scale shared computer capable of hosting the entire Internet as an application." Forget Thomas Watson apocryphal remark that the world may need only five computers. Maybe it needs just one.

The reality for most of us is far simpler. We don't need epic scale; we need to serve tens of thousands of pageviews a day. For that, almost any commodity box will do.