Google Dance – The Index Update of the Google Search Engine: Insanely technical analysis of how Google does what it does. A sample:
“For every domain www-xx.google.com, there is an additional domain www-xx2.google.com. The IP address of such a domain ends on .101 instead of .100. These pairs of domains and IP addresses belong to the same data center and, hence, the same index is searched by queries on them.”
Some people know more about Google than Google does.