mkdir -p ~/.config/compiz/ && echo SKIP_CHECKS=yes >> ~/.config/compiz/compiz-manager

Update 09 May 2009

In the new Ubuntu 9.04 Jaunty Jackalope, Intel graphic (video) drivers 965 (x3000 or x3100) are blacklisted so you cannot run Compiz thus your desktop effects cannot be enabled. There is a way to enable desktop effects, though this is not recommended because the drivers were blacklisted due to an error in xserver-xorg-video-intel and they will be whitelisted when the bug fill be fixed.But if you want to use Compiz anyway, all you have to do is type this in a terminal:Update 05 May 2009: It seems that some Intel cards now work in Ubuntu Jaunty, after the latest updates : You may also want to check out the Ubuntu graphic drivers repository