Kayak is a great company and this is a fascinating time to be in travel search. Go for it! A first job under Paul English (even a few layers beneath him) is a big win and Kayak's engineering reputation so great that you'll have plenty of opportunities down the road.
So in summary: Worst scenario is pretty darn good for you!
I wouldn't discount a company because they're competing with Google. There are a lot of companies that have competed with Google and have successfully out-competed them (likewise, there are a lot of companies that Google has acquired after failing to out-compete). You should look at Kayak on its own merits -- if the folks there are giving you a good offer, and you think the company has a good chance, then go for it.
>while the existing contract goes until 2013
I believe the consent decree was reported to say that ITA has to renew existing contracts until at least 2016. So that's 5 years before Kayak might, theoretically, lose access to QPX. Don't worry about it; 5 years of a good job is a good run.
It's not like Google has never failed at any of its ventures, but to me it seems like it might be a tough competitor to everyone in this field, since a decent amount of traffic does come through search results. On the other hand, I think a majority of users come in directly, either through WOM or advertising or previous use.
So, what is HN's thoughts on the situation for Kayak? Would it be a wrong move to accept a job there? The engineers seem smart, the work is interesting, the culture is sane and easygoing. What's the worst that could happen?