After installing CUDA on my new MacBook I tried to get also my GIMP plugin to work. I installed the latest version of GIMP from MacPorts and to my surprise the plugin just compiled and installed without any modifications. However, when I chose the plugin from the GIMP menu only the CPU version worked. Some weeks later I stumbled across a post in the NVIDIA forums, which mentioned that the toolkit installer doesn’t install the kernel extension by default. That is why CUDA didn’t work! After I installed the missing kext manually, also the plugin worked flawlessly :)
The plugin can be still downloaded here. In the meanwhile it has been also tested and reported to work on some more Linux distributions and with CUDA 2.1.
