The hybrid crossfire graphics was a technology (and still is unfortunately) where one could combine the onboard graphics such as the radeon 3200 on the 780G motherboards and combine this with a discrete graphics card for increased performance.
This was hampered by the fact that the only graphics cards you could use were low end HTPC type parts like the Radeon 3450.
I had hoped that as the integrated solutions got better (like the HD4290 found on 890GX motherboards) that they would be able to be paired with more powerful graphics cards. Unfortunately, the best card you can hybrid crossfire with still remains the 3470 I believe.
Anyway, its a useless technology that AMD would be better off not including with the boards- if nothing else to save production costs.