indeed - as these things go, that's relatively painless. (I know - I maintain the build system for balloonboard and it's a very hard thing to do well).
We (well, Jim Rayner actually) just built android for the balloon (which incidentally does produce a genuinely free platform, including GSM, although calling it a 'phone' would be a bit of stretch for most people). http://balloonboard.org/balloonwiki/AndroidBalloon