March, 2010 Wired article on Google’s algorithm.. Great read.

Hopefully this will be online soon, I’ll link it.. they are analyzing every step in the development of the algorithm, including what was (at the time) a break through synonym system:

As Google crawled and archived billions of documents and Web pages, it analyzed what words were close to each other. “Hot dog” would be found in searches that also contained “bread” and “mustard” and “baseball games” — not poached pooches. That helped the algorithm understand what “hot dog” — and millions of other terms — meant. “Today, if you type ‘Ghandi bio,’ we know that bio means biography,” Singhal says. “And if you type ‘bio warfare,’ it means biological. –From Wired