OCWorkbench has a few pictures of AMD's RD790 chipset. The big news is that CrossFire apparently works with four cards installed in either 2 by 16 or 4 by 8 mode:

The AMD RD790 chipset is an improvement over the RD580 or 580X chipset. The major difference is that it supports AM2+ and HT3.0. In the test, a AMD X2 5000+ and a pair of DDR2-667 is used. The board you see comes with 4 full length PCIe x16 slots. It is fitted with 4 graphics cards. The interesting thing is that CrossFire works even with 4 cards, but performance is not ready for 4 cards to improve the performance. The PCIe slots can be configured to run in 2 by 16 or 4 by 8 in CrossFire mode. The south bridge is still the SB600.