It's official: the free (as in freedom) edition of Ubuntu has been named Gobuntu.
Mark Shuttleworth describes in his blog:
Thanks to Colin and Evan’s efforts we now have daily images of a freedom-focused flavour of Ubuntu, “Gobuntu”. This is a call for developers who are interested in pushing the limits of content and code freedom - including firmware, content, and authoring infrastructure, to join the team and help identify places where we must separate out pieces that don’t belong in Gobuntu from the standard Ubuntu builds.
Currently, the alpha builds (based off of Ubuntu 7.10) are available, but the only modification is the lack of proprietary hardware drivers.
It seems there are no separate versions for GNOME and KDE (or XFCE, for that matter), but using the repositories you should be able to install either for the time being.