Saw this the other day.. When you search for two mayor cities in the world google now shows a flight booking ad from expedia(!), also links to hotwire and orbitz. You can enter Departure and Returning into the ad, at least I think it's an ad. Check for instance this: http://www.google.com/search?&q=london+new+york Maby this is a way google tries to get rid of the affiliate websites. First they show some adwords then some premium adwords parties like expedia and then way below the web results.
It will be cool when one day you type in where you want to go in google and you instantly go there (with a brief stop off to view a short commercial, of course)