When we reviewed Intel's Skulltrail dual-processor enthusiast platform earlier this month, we ran our tests with the D5400XS motherboard Intel designed specifically for the platform. That board is no slouch: it supports both CrossFire and SLI multi-GPU setups (although SLI capability is limited to two cards), and we were able to use it to overclock our two Core 2 Extreme QX9775 chips from 3.2GHz to a mind-blowing 4GHz.
Still, some folks planning to sink a few grand into a Skulltrail machine might be interested in shopping around, and it looks like Asus plans to address that particular demographic with its very own Skulltrail mobo—the Z7S WS. HotHardware has posted pictures of the board here, showing a more workstation-oriented offering with six FD-DIMM memory slots (instead of the four on the Intel board) and a PCI-X slot for those wanting true workstation-class expansion. The Z7S WS does have three PCI Express x16 slots (including two of the PCIe 2.0 variety), but none of them are hooked up to Nvidia switches like on the D5400XS, so you presumably won't find SLI support on the Z7S WS.
Asus' motherboard differentiates itself on the cooling front, too, with a large air cooling system for the memory and some meaty heat pipe-based heatsinks to cool the board's various chips. Where the Intel offering supports LGA775 desktop coolers, HotHardware says users of the Z7S WS will require LGA771 coolers. Nonetheless, the Asus board is reportedly significantly smaller than the D5400XS, which might allow it to fit in tighter desktop enclosures.