The Kentucky Derby is a huge deal for Louisville, Kentucky, with all sorts of people who would otherwise never visit flying in and spending lots of cash.  And the Derby’s at least a noteworthy event for Bing, too, with the folks behind Microsoft’s "decision engine" preparing some special instant answers.

At the time of writing, Google and Yahoo aren’t offering anything similar, which could give Bing a nice edge.  Even if people don’t make a permanent change, they may switch search engines for a day knowing that they’ll get more relevant results.