I like the idea. I may do my own take on a similar design, as far as designing it and doing up vectors for cutting the desktop and other stuff. likely won't build it, at least for a while. But keep on with it. looking pretty nice already. Some minor things that would make it great, IMO:
Shelves sized to accept 19 rackmounts on rails, with the rails holding in the shelves if you want, so that if you ever want to build yourself a Beowulf cluster, or just want older hardware in a semi-usable container. heck, if you build a battlebox into a good rackmount case, that could live there as well. plus it costs you nothing if you don't end up using it for racks, but saves frustration later if you do.
Second, I suggest that when/if you wire the HDD activity and power LEDs up, you put in an adjustable resistor, or something to let you adjust glow levels. i find most are too bright for me, and sometimes too dim. being able to adjust it is a minor thing, but i'd love it if more designs featured it.
Third, unless you live on Hoth, you don't want air pulled or pushed through where you are sitting. Move the radiators to the bottom of the desk surface, to warm your feet, or the back, if you can manage the clearance. If neither appeals, i'd go for setting it into the sides of the desk, pushing away from the corner, and pulling the slightly cooler air through the hardware bays.
Fourth, again hotswap bays. Put SATA pass-throughs in the side of where you want the mobo, and connect them into a bay for the harddrives. then you don't even need to open/expose the mobo when swapping, and it keeps the heat generation seperate. something like
this. Also means cables can be kept almost entirely out of sight, perhaps in ducts in the desk, so that you don't need pretty ones, and can avoid the hassles of tying/managing them in the main bay almost entirely.
Fifth, the main I/O for the motherboards should sit under the stand for the monitors. That way, no tangles of cables for vistors to pull on/complain about hanging off the side. also, less need to dust/manage/clean cobwebs off stuff you can't see.
Sixth, if you can afford it, size up a central UPS and so on, so that if you get brownouts, voltage sags, or outages, you can have graceful shutdown time. Make sure that it's the right kind. if you use PSUs for the computer with active PFC, get a pure sine UPS. if you get the UPS when you first build it, you can save some money on PSUs and the UPS by picking PSUs without active PFC, and a normal UPS.
Seventh, and I realize this is getting a bit long. Cup holders. Do it. You know you'll use them.
Eighth, Build a wired switch into the thing. run cat6 to each computer in it. that way they can all talk at max speed to each other, and no matter how you wire it to the modem, you'll saturate it if you really push, so you can save the hassle of getting one with enough LAN ports, and also have space to connect a laptop to the switch, and expand your collection of hardware in the desk. 8-16 ports is good.
Ninth, figure out the size of keyboard you prefer, and if you want to be able to use the 2+ computers in the desk at once. If so, get a KVM switch, set it under the keyboard surface to handle swapping input. put in a handy toggle on the desk surface to change it. not that challenging, if you've the manual dexterity/tools to make a good desk build. If you don't want the KVM switch, make sure there is room for 2 keyboards and mice, because otherwise you'll be into the I/O area under the monitors every time you want to switch boxes. Plan ahead for how you want to use them.
Tenth, make sure all the monitors sit firmly, and completely on the desk. Otherwise one will fall, because Murphy is a bitch. If that doesn't suit, then make sure you have at least one spare.
Eleventh, Black and red is cool. My PC, and ROG's colors are the same. But for furniture, it bears consideration. The desk will stand out no matter what color you paint it. Consider if you want it to be an invader in the room, if you can/will match the room to it, or if you want it to stand out less.
Finally, it looks damned cool already. Refine the design, pick a name, design a logo for it, or appropriate one. Something with that much investment/cool factor deserves a name, and an icon.
hopefully you do build it, because it seems like a great idea. But work out all the design work first, cause if you **** it up, it takes real work to fix a piece of furniture, and make the fixes look invisible, due to color fade if you replace the part, or seams if you just patch/recut it. plus, something this awesome deserves the forethought.