Google Sets can be used to provide external contextual information to automated object identifiers.
UCSD Researchers Give Computers Common Sense
San Diego, CA, October 17, 2007 -- Using a little-known Google Labs widget, computer scientists from UC San Diego and UCLA have brought common sense to an automated image labeling system. This common sense is the ability to use context to help identify objects in photographs.
For example, if a conventional automated object identifier has labeled a person, a tennis racket, a tennis court and a lemon in a photo, the new post-processing context check will re-label the lemon as a tennis ball.
http:///www.jacobsschool.ucsd.edu/news/news_releases/release.sfe?id=698