BillyS - 8:51 pm on May 3, 2006 (gmt 0)

I would think that the need for more machines is being driven by other products - not search.

- Images
- Maps
- Video
- Earth

All of these are somewhat recent introductions and they are all resource hogs when compared to a search index. As these become increasingly popular, the demands on their infrastructure increse.

They're also looking for ways to push their ads out to devices such as cell phones. As innovative as Google is, they are still a one-trick-pony when it comes to a revenue stream. If they are going to grow revenues, they've got to push their ads everywhere too.