Right, any worthwhile upgrade to the iBooks at this point would infringe on PowerBook territory. In fact, this dates back to about two years ago when the iBooks got ahead one revision vs. the PowerBooks (which stagnated for nearly a year with no updates). My guess is the iBooks and PowerBooks will be upgraded at the same time, within 2-3 months, and then they'll be "equal." Basically the next iBook revision should be very similar to what the 12" PowerBook is like right now.
They're not waiting for Intel processors. Apple's not going to let the iBook go another full year without an upgrade, especially since it's already been eight months since the iBook got an update. Waiting until they have Intel processors ready would mean a solid year and a half, almost two years before an update, which is completely unacceptable.