The problem with the Skulltrail board is that, while it physically holds 4 cards, it can only support them in pairs. It uses two seperate chips for SLI. You can't connect all four cards together. Therefore, you would be better off with a 790i with two 9800 GX2 cards if you want Quad-SLI or a 790i with three 8800 GTX or Ultra cards for even Triple-SLI.

I have the 780i
Sure it runs hot.
But for a $90 upgrade, that is way cheaper than $300 for a new board and $600 for the DDR3.
Ya my FSB is at 1800 and my DDR2-1000 runs in sandra in the 90's so really how much more would ddr3 help, NONE.

The 790i and skulltrail boards are on the ultra high end. Mainly because they need DDR3, which is outragously expensive and offers only a slight improvement in speed. I just built a system on the 780i board which uses ddr2. For $200 ($100 after rebate) I get 8gb of ram. The entire system is around $1800. If you wanted 8gb of ram on a 790i or skulltrail, you would have to pay probably around $1000 for the memory alone. And you don't get a lot of benifit from the extra money.

NVidia's intention to regain the crown of Intel chipset king is an indicator of Intel's supremacy in the high-end CPU and all supporting IC business. 
I give nV a few more years in chipset business, as they go deeper and deeper in General Purpose Processing Unit business. They will have API's for programming GP GPU-like chips to act as different chips; they will think a way of theaming or separating their transistors. A mobo may come populated with two of GP Processing Units, and inside each of these many Processing Units will be available to combine the processing power. They might engineer a bus for adding at least two more ad-in cards with GP chips. They will make GP chips so that they don't need any external arbitration chips. So they won't need another form of chipset to support these GP chips.

That's my vision of possible development.

"Skulltrail - supports AMD Crossfire, dual PCIe v2 x16 at that, by default. So, AMD can earn some emergency dosh by selling pairs of Crossfired FireGL high-end cards for couple a thousand bucks per Intel workstation."

The newest FireGL cards don't have Corssfire connectors. So now Crossfire love for 3D workstations. :-(

Cheers,
John