There's no word on the price Google paid, but Facebook had been in talks to acquire the company earlier this year for a reported $60 million. Presumably, Google paid more than that to keep it away from Facebook.
It sounds like Titan will work on a variety of projects for Google.Titan will be able to collect photos from around the planet from high up, which could help with Google Earth and Google Maps. It will also contribute to Google's Project Loon, which is sending balloons into the atmosphere which then beams Internet to parts of the world that are not yet connected. It's also likely to work with Makani, another company Google bought, that gets wind power high in the sky, and delivers the energy back to earth through a long cable.