I can confirm this issue using the Lucid Lynx installation and the nvidia-current(nvidia-graphics-drivers-190) drivers. I do have the message when checking under "System -> Administration -> Hardware Drivers", 'This driver is activated but not currently in use.' No desktop effects can be enabled. However, I can now activate the desktop effects in "System -> Preferences -> Appearances".
I can confirm this issue using the Lucid Lynx installation and the nvidia- current( nvidia- graphics- drivers- 190) drivers. I do have the message when checking under "System -> Administration -> Hardware Drivers", 'This driver is activated but not currently in use.' No desktop effects can be enabled. However, I can now activate the desktop effects in "System -> Preferences -> Appearances".