I noticed that the upgrade for Oneiric was available, so I decided to jump in & upgrade my Ubuntu machines. It has become the habit that I encounter all weird stuff & errors during such upgrades, but that's something specific to me, it seems ;)
On my desktop, I returned to the installation program 2 hours later after I started it, only to find a black screen with a mouse pointer. No possibility to restore the screen, so I had no other choice than to kill X, and resort to command-line mockery. I've learned by previous experience that rebooting the machine or restarting X at this point lead to major mayhem on my desktop, so I entered 'dpkg-reconfigure -a' to complete the setup, which it actually did, to my big surprise.
Since Natty, there has been much turmoil on the internetz about something Canonical enforced to the enduser, called Unity. I have skipped this enforced desktop in the past by reverting to the Gnome legacy mode, but it seemed that this was completely foobarred in the current Gnome3 in Oneiric. So what has a man to do in a completely changed environment ? Adapt. I decided actually to try out Unity, and lo and behold, it was actually quite usable. Unfortunately, Unity does not support gnome applets, but I resolved this by running Conky, which adds extra panache to the desktop experience.
There are off course still quirks in Unity. Mocking around with the Compizconfig settings can ruin your desktop experience, although not so disastrous as in Natty. On my netbook, Unity refused to start up, leaving me only with a empty wallpaper. I resolved this by setting the LIBGL_ALWAYS_INDIRECT=1 envvar in my .bashrc.
We'll see how this Gnome3/Unity combination goes. If it really turns out to be an atrocity, there's always KDE or XFCE to revert too...