The announcement was made by Dave Bort, Google software engineer:

“Today is a big day for Android, the Open Handset Alliance, and the open-source community. All of the work that we’ve poured into the mobile platform is now officially available, for free, as the Android Open Source Project.[…]

Have a great idea for a new feature? Add it! As an open source project, the best part is that anyone can contribute to Android and influence its direction. And if the platform becomes as ubiquitous as I hope it will, you may end up influencing the future of mobile devices as a whole.”

The move is hardly a surprise for developers. Google has announced long before that the final step towards open source would be made at some point during the fourth quarter. Previously, developers only had access to the Software Development Kit (SDK).

Be warned though, those willing to play with the code must face two drawbacks. First of all, the code weighs a hefty 2.1 gigabytes. Second, the code only works under Ubuntu and it will only work if you have a Git open-source version-control system.