Many of us had predicted that Steve Jobs would unveil new PowerBooks at Apple Expo, but he then went and cancelled his keynote. One can only guess that there was some unforeseen problem which caused a delay in the release of these (and other) new Macs. However, new updated PowerBooks may be coming very soon.
First of all, now if one orders the upper end 15" PowerBook with any upgrade option, shipping times increase to 2-3 weeks. The shipping times are much lower for other build-to-order Macs. Furthermore, AI reports that the as yet unreleased OS X 10.4.3 contains references to new PowerBook models. The last PowerBook update was in January, 9 months ago.
What these PowerBooks will get as upgrades is unknown, but I would expect:
Up to 1.8 GHz G4 7448, with 1 MB L2 cache and 200 MHz bus.
512 MB RAM built-in on all PowerBooks. (The 12" has 256 MB built-in.)
New GPUs, especially on the 12" (which has a worse GPU than the iBook).
Possibly a higher screen resolution option for the PowerBook 17".
These would likely represent the last of the PowerPC based PowerBooks. It's likely that Apple will release new PowerBooks in the first half of 2006 which utilize Intel's new dual-core Yonah laptop CPUs. Since the new Yonah machines will be much faster than any of today's single-core PowerPC PowerBooks, many may want to wait until the Intel PowerBooks are released before upgrading. However, those with the least bit of concern for software compatibility or who require Classic support would be best advised to buy the last of the PowerPC PowerBooks. In the near term, the current G4 7447A and upcoming G4 7448 PowerBooks will encounter fewer compatibility problems than next year's Intel PowerBooks.
New machines may come as early as October, although it would not be surprising to see the upgraded PowerBooks hit the streets a short while later.