According to both Adobe and nVidia, the Mercury Engine will ONLY work with an nVidia Quadro card. The nVidia Quadro 4800 that was being used in the demo is $1,550 from Newegg. For an additional $1,550 one should certainly expect an increase in performance. There are less expensive Quadro cards, but I'm not sure which Quadro is required at a minimum and how much of a performance boost the minimum card would get you. There is also the matter of having to use Premiere to edit video...

For $1550 - or $550 for that matter - I'd rather transcode, thank you very much.

Although I do hope AVCHD performance in Vegas gets better. Soon.

The thread on the Adobe message board (and a similar thread on Dvinfo.net) states the same thing, that only four, presently available nVidia video cards are certified to work with the CS5 Mercury engine (GTX 285 and the Quadro 3800, 4800 and 5800). That doesn't necessarily mean that other CUDA-enabled cards won't work, but rather, Adobe does not "support" their use.

The soon to be released Fermi cards (GTX 470 and GTX 480) will likely also be certified by Adobe, as will the new Quadro cards, that are based on Fermi. The pro cards tend to have more RAM and I suspect, they will be able to do the full complement of the Mercury engine provides. The consumer cards like the GTX 285, will still work, but probably not as robustly.

Further, Adobe doesn't have a great track record with hardware video acceleration and its CS series. To date, the only truly reliable acceleration was provided for Premiere Pro CS3 and that was done by Cineform, not Adobe. CS4 has a 3rd party hardware video card encoding (not previewing) solution, but everything online says it was overpriced and buggy. It remains to be seen how effective the Mercury engine will be in speeding up previews, since Adobe is at the mercy of nVidia and it's video card drivers.

And as to encoding, each codec would have to be CUDA-enabled and I doubt that we will see that for a while, at least not from Adobe and certainly not for free.