Nonlinear has a post on a post from Grant Petty the CEO of BlackMagic saying that the full version of DaVinci 10 will support the Dual AMD GPU’s of the new MacPros. And Premiere Pro already supports AMD Firepros, and hopefully will soon support the duals of the new MacPro.
I will still rather see Dual NVIDIA GPU support, as CUDA would likely be faster, but this could make the MacPro a viable alternative to the current MacPro without the expansion. Still want to see some speed tests though as I would like to see Premiere Pro rocking Dual Titans!