Google launched its desktop-only Flight Search service last year, to the chagrin of some big competitors, and now it's updated the tool to work on Android and iOS devices. The service works through Google's standard search box or on its flights page, and the update only optimizes the tool for use on mobile devices (it's not a standalone app). After giving it a brief spin on an Android and iOS handset, it looks like the core functionality's all there, including flight search, location-based flight discovery, and price, airline, and calendar filtering. But don't expect it to find flights to anywhere in the world just yet.
Unfortunately, Flight Search is still a relatively incomplete product — Google still hasn't included international flights, and even some domestic carriers like Southwest and JetBlue aren't participating as of yet. The update post from a Google engineer tells a story about how a friend's recent trip to Maui inspired him to check for flights to Hawaii at home. He can now search on his mobile device, too — but Google will have to actually include flights to Hawaii first.