Google Universal Search Element: Flights
As an example of Universal Search, Google is showing a special area at the top of the page that let's you directly search for flights to San Francisco. I found it on a search for Chicago to San Francisco (no keywords associated with travel you notice). They list the top travel sites (not the airlines) as secondary links, but the primarily link from the special area goes to Expedia. TripAdvisor is not on that list. And why Expedia? Are the travel sites paying to have that link? What other special areas are like this in that Google has chosen a number of sites to highlight with an interactive element?
Image of Special Flight Area: