The Google Web Fonts project - recently renamed Google Fonts - has done a deal with font service Monotype to make its free fonts available for desktop use.
Monotype's SkyFonts software is normally used to rent commercial fonts for short-term use. But the new deal means you can access desktop versions of the 624 Google Fonts - previously only available for use as web fonts - via SkyFonts, for as long as you want.
Using SkyFonts will also ensure you always have the latest versions of the fonts, as it will automatically update them when new characters are added. You can find out more details of the new service and start downloading the free fonts here.