Found a nice page on how the PS3 works at "How Stuff Works".
It has some nice pictures of the processor itself, with neat eye candy when discussing the PS3 GPU RSX "Reality Synthesize". You should check it out .. if nothing else but to seen the impressive graphics.
Keep in mind that until Sony or a third party creates libraries optimized for the cell (and drivers for the GPU) ... the Linux side of life won't be all that impressive. This is why I believe the currently working MythTV frontends on PS3 are a little slow / choppy. Frame buffering .. although useful as an easy first port .. is hardly efficient.