At Web Certain, we have been predicting, literally for years, that we should expect to see the emergence of vertical - i.e. sector-specific search engines. AOL is already heading in that direction and not surprisingly starting with travel powered by Kayak - a recent AOL aquisition.
The new project has been launched in Beta - and is known as Pinpoint Travel.
There will be more of these for sure. Expect further launches from Yahoo, MSN and Google in the coming months - notwithstanding all the potential market newcomers!