Internally, this has been around for a little while (disclaimer: I work for Google but not on anything related to this). What continues to impress me about Google is: 1. Just how quickly this was built (really, it was quick); and 2. Google wants you to use our services because they're compelling not because we don't give you any other choice (ie "Don't be evil"). Sure there are limits to what it currently does but I…
Wouldn't this have to be thanks to their relatively recent ITA acquisition? Not too surprised since QPX runs a few popular websites such as Orbitz and Kayak.
(I'm not saying it's not a feat to do it in such little time as any project does take time, but I would like to see credit where due.)