This short write up on HBS's Cyberposium panel titled "Search Visionary" holds a few interesting snippets that may prove insightful when looking at where Search is headed. Particularly this bit from Yahoo's Bradley Horowitz:

Yahoo is able to collect data, such as click patterns, from its users and use the information to individually "tune" searches to users' personal tendencies. Such product improvements, [Yahoo Director Bradley] Horowitz said, will change the nature of search from a one-size-fits-all experience to a more individually oriented one.

Also stuff in there from Ask, MSN and Google - thanks Greg