i attempted an upgrade to jaunty (9.04), too, and - i admit - canceled it with "cancel" button while it was downloading (it didn't seem that absurd). it stated it was "partially upgraded" or "updated" or it can be "only partially upgraded". anyway, the problem is after some restart it didn't boot properly, showing only the items on the desktop after login and no controls at all.
however: after previous, seemingly succesful upgrade to 8.10, the system was anyway unable to shut off properly, always ending with a freeze (at various stages).
i therefore victoriously managed to set up (with wep key) and connect my wifi card working at console, reached through root prompt of the recovery mode, and ordered upgrade to 9.04. it worked, however it seemed to give errors here and there - i wasn't able to follow the changes for many hours. but the upgrade didn't help this time, and there's mess with xserver-xorg.
i tried both 'dpkg --configure -a' in recovery mode root prompt and dpkg option of the recovery menu, but it always ends with "Fixing recursive fault but reboot is needed!" with freeze when quitting with 'ctrl+alt+del'.
aptitude asks for 'dpkg --configure -a' and states there are "95 partially installed packages" including 'xserver-xorg' which it can't fix when tries.
what i wonder about, is this bug, since i have similar dpkg problems on tower pc , and i specifically remember being stuck while openoffice.org installing/configuring.