Yes, you're looking at ITA's InstaSearch product, which delivers near real-time results, compared to the traditional QPX product.
There were many articles about Google's acquisition of ITA, and various stipulations around InstaSearch:
"As a condition of the deal, Google must continue to license ITA's QPX software for airfare websites on "fair, reasonable, and non-discriminatory terms" through 2016. And it must commit to continued investment in ITA's QPX software and in ITA's unreleased InstaSearch product, which aims to provide near instant airline fare quotes."
It probably is caching data from other people's searches, similar to what Kayak does. This is cool right up until you try to actually book a flight and it sells out or goes up in price dramatically.
