It had an unlockable bootloader and openly flashable recovery. Additionally, Google themselves have responded to the complaint that the builds are missing some

It had an unlockable bootloader and openly flashable recovery. Additionally, Google themselves have responded to the complaint that the builds are missing some bits. They have taken steps to remove those hooks as being necessary, and some of the pieces of the bootstrap are not their property to place in AOSP. That having been said, CM had a build running on his Nexus One within hours of source being released...