Please correct me if I'm wrong, but developing a good Android launcher, with all the features we all loves (gestures, etc), seems to be a far more easiest thing than coding a whole OS. And starting with such fundation would give support of Android applications "from scratch", without having to rely on tweaks like Alien Dalvik, sfdroid, etc. Packaging such Android distro would also be far easier and support of various phones would not be a problem anymore.