Google Fellow Jeff Dean gave a talk at Stanford for the EE380 class with fascinating details on Google's systems and infrastructure. Krishna Sankar has a good summary along with a link to video (Windows Media) of the talk.
Some fun statistics in there. Most amazing are the improvements in data processing that have gotten them to the point that, in May 2010, 4.4M MapReduce jobs consumed 39k machine years of computation and processed nearly an exabyte (1k petabytes) of data that month. Remarkable amount of data munching going on at Google.
The talk is an updated version of Jeff's other recent talks such as his LADIS 2009 keynote, WSDM 2009 keynote, and 2008 UW CS lecture.
[HT, High Scalability, for the pointer to Krishna Sankar's notes]