You didn't have either x-window-system-core (which ubuntu-desktop depends on) or ubuntu-desktop itself installed. The move to an "xorg" package happened in edgy, so if you didn't have the correct metapackage installed, you might very well end up with missing pieces. Also, note that apt-get -f install is quite likely to have removed some packages at a point during your upgrades, so unless you have a log which shows exactly what you did, I'm inclined to put this down to user error.
** Changed in: xorg (Ubuntu) Assignee: Simon Law => Tollef Fog Heen Status: Needs Info => Rejected -- upgrade from dapper misses xorg dependencies https://launchpad.net/bugs/58505 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs