Whats the last OS X that supported Power PC?
Snow Leopard (OS X 10.6) is also the
  first Mac OS release since the
  introduction of System 7.1.2 that
  does not support the PowerPC
  architecture, as Apple now intends to
  focus on its current line of
  Intel-based products.


Thus OS X supported PowerPC up to and including version 10.5 (Leopard).