Apple’s been mum about the rumors that the next version of Mac OS X — Snow Leopard — will not support PowerPC machines, but the webpage describing the new OS may hold a clue:

Snow Leopard dramatically reduces the footprint of Mac OS X, making it even more efficient for users, and giving them back valuable hard drive space for their music and photos.

Taking all that PowerPC code out of your OS would certainly go a long way towards reducing its footprint now, wouldn’t it?