For those of you interested in speeding up your h.264 rendering of the time line, using CUDA, MainConcept has announced two new products:
http://finance.yahoo.com/news/MainConcept-Announces-Two-New-prnews-671828689.html?x=0&.v=1
Here's the overview for the CS5-specific pack. There is a watermarked fully functional demo. Unfortunately, outputting h.264 BluRay compliant streams is not supported in this release (demo or otherwise).
The 2nd product is an upgrade to the MC Reference, which also has the CUDA-based h.264 codec and also has a demo. The MC reference is a high-end product.
Note, that these products are for Windows.