MacBidouille and AppleInsider have both posted similar reports regarding the ongoing PowerBook wait.
MacBidouille claims that due to Motorola's inability to produce PPC7457s in large volumes, PowerBooks will be delayed until mid-October. While AppleInsider, also citing reliable sources, confirms that low processor supplies are the cause of the delays, but provides no time-frame for delivery.
Meanwhile, both sites suggest that G5-based PowerBooks may be deliverable in early 2004.
Motorola's Power PC 7457 is the rumored chip that is to be used in the delayed revision of PowerBooks.