The news recently came out that the PS3 will feature a 60GB HDD and will run Linux. This is quite interesting to me, since it raises the possibility of running Blender on the PS3. The cell processor is theoretically ideal for jobs like rendering, if Blender can take advantage of its very parallel nature.
The PS3 also only has 256MB of memory, so you would probably need to swap to HDD, or find some way to upgrade the RAM.
But if it was possible to get Blender fully using the PS3’s resources, I think you would end up with the equivalent of a 2 or 3 thousand dollar (for rendering purposes) machine, for only $500.
I’d buy eight of them and stack them up as a render farm