Nvidia nForce4 motherboard chipset with SLI support... and true to their usual level of quality, Tyan has hacked it up a bit and added TWO PCI-Express controllers, making this the only motherboard that has two full PCI-Express slots each with 16 PCI-E lanes of bandwidth. Other vendors with dual PCI-E put one controller on the board and split the lanes in half, 8 per slot. While this is fine for lower end cards, it'll hamper the performance of the really high end cards coming out. Current PCI-E graphics cards barely use 4 lanes, the next gen (coming out now and first quarter of next year) will likely use 8, the one after that (think middle or end of next year) will want the full 16. This motherboard is the only one that will be on the entire market which is capable of running a pair of SLI-capable PCI-E graphics cards at their absolute maximum performance.
A nice side benefit to having a pair of SLI graphics cards is that when you're not gaming (and using all that power to draw one image on one monitor), you can run four monitors off of the rig (two per graphics card, most require DVI). It's a true hydra.
It'd also be perfect for someone who wants to use the newer PCI-E sound cards in a system designed for high quality studio sound production, and still have their rig be capable of doing some serious gaming. PCI-E sound cards are supposedly able to keep the noise level down to near-zero. With one high-end graphics card and one high end sound card, you'd be set.
As you can see, the sucker will handle a truckload of RAM, up to 16GB, or even 64GB if their engineers are feeling frisky. Opteron chips are capable of addressing as much ram as you want to stick in the system. This is a video enthusiast's dream platform. Onboard SATA-II (which crushes SCSI to dust for bandwidth), a pair of 64bit Opteron CPUs... if you can manage to max this thing out with any task you're doing well. All it needs is a large disk array, and for that you're always better off buying a raid card like 3Ware's 8000 series than using the cheap onboard raid.
I would be willing to bet that this motherboard, when fully populated, will not become obsolete for 10 years. The worst case is that you may need to upgrade the graphics cards in the first five years, but those cards will still work perfectly in this model because it has all 16 lanes available. It will come with Tyan's standard 5-year warranty so there's good security to it as well.
The only downside is that your wallet will be a lot lighter after buying it. This board is likely to retail for $500 for the workstation model, and $800 for the server model. Well worth it IMO if you consider it to be a 5-8 year investment. It'll need a very expensive power supply as well, you're looking at a 550w model. It'll be the worst space heater yet by far, but quiet if you buy the right cooling products.
There are rumors indicating Tyan is also planning to release a version of this board in the next few months that supports dual-core Opteron CPUs. That would effectively give you a quad-CPU system, low-end supercomputing under your desk, for somewhere in the neighborhood of $2500.