Engadget posted the first sighting of the Radeon 6990. It has 4x Mini-DP and 1xDL-DVI. This would seem to support 5x1 on the Dual-GPU Radoen 6990. It also requires 8-pin + 6-pin auxillary power. This is the same power requirements as the Dual-GPU 5970 and the recent NVIDIA GTX580.
While I'm glad to see the 5x1 support, I am disappointed at the cable configuration. I already spent money on Mini-DP > DP cables for Radeon 5870 E6, so that I could run everything off of DP connections. I already have my Mac Pro running on the DVI ports on the monitors. Considering there is no option to convert DVI > DP, I'll have to swap cables around and be inconsistent in my connections between my PC and Mac.
I get that 5xMini-DP + 1xDVI wouldn't all fit on one half of the card. And, I get how having a DVI connection makes it easy for single monitor users - but adapters dirt cheap now. Nothing deal-breaking, but it would have been nice for AMD to be consistent in their cabling from one generation to the next.
http://www.engadget.com/2011/01/26/amd-radeon-hd-6990-shows-up-in-its-metallic-flesh-looking-large/
http://www.4gamer.net/games/122/G012292/20110126021/