None so far. Reverted to the 185 Nvidia release, the one included in Ubuntu Karmic. I tried to use Karmic and the latest nouveau drivers (see
http://nouveau.freedesktop.org/wiki/UbuntuPackages) without success.
I also tried Lucid with nouveau. Works so far, X seems stable, but suspend/resume also only works once. But Lucid is currently for some other reason (nothing to do with NVidia) no option for me.
Does anyone run Karmic with nouveau?