As far as console hardware goes, the engine is already running on Xbox 360, with support for six simultaneous threads. The PC platform and Xbox 360 are apparently close enough that getting the software to run on both of them does not require a lot of extra effort. PS3 on the other hand.... The potential to support PS3 is definitely there, but it doesn't sound like Valve has devoted any serious effort into this platform as of yet. Given that the hardware isn't available for consumer purchase yet, that might make sense. The PS3 Cell processor does add some additional problems in terms of multithreading support. First, unlike Xbox 360 and PC processors, the processor cores available in Cell are not all equivalent. That means they will have to spend additional effort making sure that the software is aware of what cores can do what sort of tasks best (or at all as the case may be). Another problem that Cell creates is that there's not a coherent view of memory. Each core has its own dedicated high-speed local memory, so all of that has to be managed along with worrying about threading and execution capabilities. Basically, PS3/Cell takes the problems inherent with multithreading and adds a few more, so getting optimal utilization of the Cell processor is going to be even more difficult.
