they use small feathered dinosaurs
the picture is priceless
http://www.google.com/technology/pigeonrank.html
As a Google user, you're familiar with the speed and accuracy of a Google
search. How exactly does Google manage to find the right results for every
query as quickly as it does? The heart of Google's search technology is
PigeonRank, a system for ranking web pages developed by Google founders
Larry Page and Sergey Brin at Stanford University.
Building upon the breakthrough work of B. F. Skinner, Page and Brin
reasoned that low cost pigeon clusters (PCs) could be used to compute the
relative value of web pages faster than human editors or machine-based
algorithms. And while Google has dozens of engineers working to improve
every aspect of our service on a daily basis, PigeonRank continues to
provide the basis for all of our web search tools.
...