Grist for the mill, but the 14" iBook does have the best battery life of any Apple laptop.
But if you plan to use if for a few years, the 64MB VRAM in the PowerBook might be the dealmaker (plus mini-DVI out for external digital display vs analog-XGA-out on the iBook).
If you plan on using it with an external display, the VRAM in the PB has double to share.
VRAM is not upgradeable later, and the minimum spec for many games may move to 64MB VRAM by next year...
For future proofing reasons in the graphics end, I'd consider the PB, but if you're leaning towards lounging student surfer use, the extra juice in the iBook might mean another half hour between charges (depending on tasks and energy saver/brightness settings).
Not sure how much that helps.
