I'm always excited when I see people inventing new uses for existing devices. Linux kernel developers have been working hard, and have now added PS3 support for the Linux kernel. Sony helped by contributing patches for the machine, which have now been merged into the kernel. This will be included in the Linux kernel 2.6.20 release. The kernel patches which were merged into the kernel can be viewed here:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f58a9d171a346afb1b09190427e6c28c6118703e
The cell processor, which is the CPU that exists inside the Playstation 3, is a multicore CPU, with 64 bit support and a PowerPC base. The cell gained Linux support last June, and was released in the 2.6.13 Linux kernel. Porting the kernel to this architechture was not difficult, as the core difficulty was making it 64-bit, and that has been a feature in Linux kernels for years. This left simply porting to a PowerPC processor, which is nothing new (previous Macs had PowerPC processors). A special Cell team helped immensly with the port.
With Sony's recent patch, you get additional hardware-specific and core support for the Playstation 3. Also, it provides extra memory-structure features, direct memory access, and symmetric multiprocessing.
The reason for this merging is because simply having patches often causes kernel conflicts, compilation problems, and having one standard kernel which runs on both regular PCs and the PS3 is much simpler. Although many people will prefer to stick with the default PS3 firmware, I think that Linux support on a game console is a great idea. It allows you to get the best out of both worlds: gaming, and when you're done with that, you can boot into Linux and get some real work done.
What's next? I'm eagerly looking forward to Wii and Xbox 360 support built into the kernel. Then again, maybe this is just wishful thinking.