do you think blizzard will make it intel only? it seems like it would be easier to do, but would they leave us out in the cold for not having a x86 processor?
Regarding PowerPC, it's a pretty safe bet that SC2 will not be able to run on a G3 or G4, so that leaves the G5 type systems.
The game is graphically intensive enough that it will likely require the benefits of multi-threaded OpenGL, which isn't available on G5 until Leopard ships, and will not benefit single-processor G5 machines. So, single processor G5 iMacs and towers are probably no-go.
So, this leaves us with tower (dual core) G5 PowerMacs running Leopard, as probably the lowest PowerPC system we could support with SC2.
Note that SC2 is not shipping this month or anything like that, as was pointed out in interviews online, we have a lot of content yet to complete, and we have not yet made any permanent choices about which hardware will be supported. No release date has been announced.
We'll be watching the hardware surveys on WoW over the coming months to see what the breakdown of Mac hardware is and what the trends are. Obviously Intel is growing very rapidly this year among that user base.