Just like they bought Picasa (now free, though you pay for Picasa Web Albums if you want to store a lot on there), Keyhole (now Google Earth; premium versions are available but most folks get it for free) and other companies that I've now forgotten about...
They also provide a ton of other apps for free as well.
I've just got one question: Why don't you do your job for free? -- DSLR Mafia My Blog - Raising Connor WoW: Mal'Ganis : Aftershock : Krimdal