Hi. I found some info:
http://www.linuxfordevices.com/c/a/News/Tilera-TileGx/
The cores are MIPS based, and are optimized for streaming data. So, it probably would be pretty weak running an OS. (The Cell BBe in the PlayStation 3 has the same issue, though the Cell 8i is supposed to make a robust workstation.) They do apparently have floating point capability, which is good, but I don't know how powerful. The Tile processor cards are already available in 32-bit flavors, including a 6x6 (36 core) model.
It looks like it runs its own compile of Linux, so one probably could not just throw Debian MIPS on it. If they become popular in research as a co-processor card, then it may be worth BOINC'ing on it. Otherwise, unfortunatley, it seems all computation is converging on Intel. ATI and nVidia show some promise. The Cell did, but that seemed to be eclipsed by the nVidia CUDA environment. China's Godson 3 processor *might* be something different, but the 2F seemed to fizzle.
Personally, I think some diversity in the ecosystem would be a good thing. I would consider getting a second PS3 (an older one with the PS2 chipset!) if I could get a robust BOINC client on it. I would also get an XBox 360 if I could cruch or fold on it.