like new hardware always ends up being leaked out to one or the other website before launch and this time it's OCWorkbench that's got its mitts on an early sample of an RD790 board from AMD.
The pictures are far from revealing, although the board in question is meant to use socket AM2+ and HyperThreading 3. It's very much an engineering sample and judging by the layout, it does look similar to past reference boards from ATI/AMD, in other words a rather odd layout.
There are no full board shots, but OCWorkbench has some interesting screen shots of the board running quad Crossfire. This is supposedly possible due to the ability to split the bandwidth of the PCI Express slots so the board either has two x16 slots or four x8 slots.
The current Catalyst drivers doesn't give you any performance benefit with four cards over two cards, but this is at least promising for users of dual chip cards, since it sounds like AMD is considering drivers with support for four GPU's.
You can see a couple of poor quality pictures and some screen shots here