Group Of Enthusiastic Hackers On The Roll - The Replicant Project

Heard of the Replicant project?
Replicant is a completely free distribution of Android already up and running on several devices.

The Replicant project was founded by Bradley M. Kuhn, Aaron Williamson, Graziano Sorbaioli, Denis Carikl. They are no private organization or company but instead a group of highly skilled developers/hackers who have given Android a new face. They intend to make the platform completely open source through their distribution.

They have their own SDK with which you can write apps for different versions of Replicant, the SDK is similar to Android SDK except that it is totally free and even comes with an emulator for those without a phone to test on. They have created an app similar to Play Store which comes default on all Android phones called FDroid which will only contain apps listed under free software license.

They have released several images of Replicant for various devices and continues to develop for more. Visit their Wiki for a detailed list of supported devices.
List of the bare minimum requirements for a device to be ported to Replicant:

• The device must be supported by CyanogenMod officially (better) or via 3rd party repos
• There must be a way to flash images (via bootloader or recovery) using a free program
• The kernel must not be signed: the bootloader must not check the kernel signature
• The kernel sources must have been released
• The network type must be GSM, no CDMA phone can be supported for now

Anyone interested in porting Replicant to their devices are welcome to do so and can use their help. For more info on targets for Replicant refer this link. The project is not backed by any corporate and is a  purely  community based one and hence requires maximum support.