Ubuntu has this script called ppa-purge in repos and that might be a good reference if someone starts to build script for N900. Ppa-purge downgrades all packages coming from PPA's (Personal Package Archive) to standard ubuntu packages (i.e. to more stable and tested version) so it's not exactly the thing benny was after but in a way it's similar. http://bazaar.launchpad.net/~xorg-ed...d%3A/ppa-purge