Google's latest product is Google Flight Search, which will let you search through multiple airlines for flights so you get the best price. Yep, just like Kayak, Orbitz, Travelocity and other such sites.
Google is hoping to stand above the crowd with a clean interface and some neat features. One lets you put in a departure city, then view potential destinations on a map. You can restrict the search by price and flight time to narrow things down.
It's all very Googley, integrated directly into search and heavily using Google Maps. Is it really that much better than existing sites? Not really. But the fact that it's Google should make sure it's used despite that fact.