I am experiencing difficulties with the nvidia proprietory driver since the update too. If I try to login to the standard 3d desktop I get nothing but a black screen and a mouse cursor.
Oddly though I belive the desktop is "there" just not showing up as, randomly clicking around, I managed to create a new folder on the desktop while the screen was black.
Hitting ctrl + alt + f1, logging in and restarting the desktop manager (by the way that's not gdm any more Bluphx it's lightdm) with:
I can then log back in using the 2d desktop without any trouble.
sudo service lightdm restart
I'm currently reinstalling the nvidia-current package - after a complete purge using:
I'll see if that helps at all.
sudo apt-get purge nvidia-current
I'm using an Nvidia 6100 Go (old I know but so's my laptop!)
If this persists I guess it'll be time to revert back to the nouveau driver until a new driver or compiz fix is uploaded. It seems to handle the 3d desktop ok, just not as fast as I'd like!