searching web pages, but not on storing and searching (or otherwise
analyzing) searches (user search phrases)?
What do they do here? Do they use the same technologies as for pages?  
Store it in BigTable? Analyze it using MapReduce? Do they compute a  
"SearchRank", i.e. the rank of a page based on how often it is clicked  
when presented as part of a search result set? Do they take combine  
this with the page's PageRank before displaying the TopK results?
What other analytics do they perform on search results? User-visible  
"analytics" examples include Google Trends and  Zeitgeist but those  
are just pure aggregation and ordering.