I didn’t get to cover this one, but Lisa Barone for Bruce Clay, Inc. did a great job:

http://www.bruceclay.com/blog/archives/2008/08/semantic_search.html

What is semantic search? A way of finding meaning in those 2-3 words you type in the search bar. Search for ‘Definitely, Maybe’, you get music-related results  for Oasis. Search for ‘Marriott San Francisco’ and you get a hotel listing with a map. You’ve probably seen a lot of this in place already. The idea is to move away from ‘blue line’ listings (ie. the standard link and snippet the search engines normally display).

How will it work?
Well, publishers have to do some work to tag and categorize content. Microformats and Yahoo’s SearchMonkey are evolving tools in this space. Check out Hakia and Powerset for examples of other players.