Toast 11 (mac) for example uses CUDA(Mac) to speedup h.264 encoding.
http://developer.nvi...oolkit-41#MacOS (10.6.8+ needed)
For Enduser usage you only need the CUDA driver, not the SDK.
Dev driver is named: devdriver_4.1.21_macos.dmg (last was 4.0.50)
To check CUDA on OS X you can use CUDA-Z tool (DL at the end) which shows informations about the CUDA gpu and has small CUDA (VRAM + PCI Transfer speed) benchmark.
Bildschirmfoto 2011-12-06 um 11.31.38.jpg 68.73KB 208 downloads
EDIT: now 4.1.28 available, 26.01.2012