a post on HKEPC, AMD's upcoming RS780 chipset will be available in two different versions, the plain RS780 as well as the RS780D, which adds support for two PCIe x16 slots for CrossFireX.
Both chipsets will feature integrated graphics and both will be able to do Hybrid CrossFire, but the RS780D will apparently get a faster graphics core.
The RS780 chipset in Hybrid CrossFire should offer some extra performance no matter what ATI graphics card you add, although the more basic the graphics card is, the more of a performance increase you will see.
It will be interesting to see who comes out as the winner here, as Nvidia will have its own Hybrid SLI solution ready to compete with AMD; although it looks as if Nvidia is going slightly higher-end with its 780a chipset than AMD is with its RS780D.
You can find a babelfish translation of the HKEPC article here