Gordon Fischer reflects:
"According to Paul Strassmann's lecture, a standard Google Cluster contains 359 racks with 31654 machines.

He also mentions that there are ">12" data centers around the globe. Assuming each data center has at least one Google Cluster that means that Google is operating > 379848 individual machines.

Video of the lecture is also available at strassmann.com."
roughtype.com/archives/2006/03 ...

See also:
divedi.blogspot.com/2006/03/al ...