This MacCentral article discusses Apple use the G5 and provides some candid information on upcoming use.
Greg Joswiak, Apple's vice president of Hardware Product Marketing says:
"Our partnership with Motorola is not going away, G4s are in every other part of our product line. As you can see, [the G5] is not going in a PowerBook anytime soon. Motorola remains very important to us, but IBM is the one that can take us to the next level."
MacWhispers had been the only rumor site claiming that 970-based Powerbooks were currently in production -- and likely to arrive at WWDC. These reports had been considered unreliable as MacWhispers has been consistently inaccurate with their rumors.
While the PowerBook was not refreshed at WWDC, 15" G4 PowerBook updates are still expected in the coming weeks, as reflected in our Buyer's Guide.