With version 3.3 of the Linux kernel, some Android code has finally made it into the Linux kernel.
According to the official release notes for V3.3:
“For a long time, code from the Android project has not been merged back to the Linux repositories due to disagreement between developers from both projects. Fortunately, after several years the differences are being ironed out. Various Android subsystems and features have already been merged, and more will follow in the future. This will make things easier for everybody, including the Android dev community, or Linux distributions that want to support Android programs.”