It is not as simple as which cards ( or Technology : ie CGPU, CUDA, OpenGL 2.x, Elemental Bada-Boom\RapiHD Accelerator ) will CS4 support. They're stating different requirements for GPU Acceleration in Photoshop, Premiere Pro, and After Effects. And it's looking like only a Quadro will cover all the technologies coming out of the gate. But again I emphasize that they haven't put out enough info to help anyone choose(or decide against) a new card yet.
After my first post I searched adobe's site again for specs and benefits of CGPU choices in Premiere Pro CS4 and again found that they have still not updated their tested cards from version CS3, and most of those cards are aged 2 years or more.
Shouldn't the testing and validating be done prior to the release of a product if they are claiming the goose poops gold nuggets? They should have a list of cards, chipsets and motherboards that ring the cherries. That's what every hardware vendor supplying 3rd party tools does ( Nvidia not included )
From my own experience putting together Adobe based edit stations over the last five years I can state that only intel chipsets are a sure bet with Premiere. I've worked with two systems, one with a Nvidia chipset and one with an AMD\ATI chipset, that both would have overlay issues and crash often. The NForce system would even have stuttered playback and have DV stream dropouts while editing. After way too much time trouble shooting I found that I needed to turn off GPU acceleration all together to make the systems behave. Both cases were working with the CS2 suite. I would not try to make an absolute case against amd processor solutions because I also work with an Opteron system (2x dual cores, Pre Barcelona) that works beautifully. Oddly enough that system has an expensive Fire GL card that has issues with After Effects.
So it's the lack of information that is my issue with both adobe and Nvidia. There has been more damn marketing articles splashed all over the DCC and computing sites but no clear specifications or benefits of one gpu over another spelled out.
I see I'm writing in circles now. It reminds me of searching for info at the Adobe site. F' those guys for giving me a headache.