imho, the only reason to get the PB is for FCP! The faster RAM, HD, vid card, and screen real estate will help with the rendering and room for all the controls.
The case can also be made for games on a Mac (such as my favorite, WoW) however a college student who plays games generally plays more than one and since the selection of games on a mac is limited, that will usually drive the student to get a PC. Sad but true. 🙁 Most gamers I think will have two machines. Their mac which is used for everything except games. And then a cheap pc to satify their craving on 🙂
However for EVERYTHING else, i would recommend the iBook. The difference in the specs is not worth the price premium of the PB for what a typical college student will be doing. Most college students will not have gig-eth in their dorms. The faster components won't fetch your email noticably faster, nor will the 1" smaller screen prevent you from seeing 'normal' websites as they are usually coded for 1024x768 or 800x600 anyway. When I started college I got a brand new TiBook 500 which at the time was light years ahead of the iBook, mainly because the iBook was still using a G3 proc. Now the differences are so small I only see one option for the average college student, the iBook. If I were to get another Mac laptop RIGHT NOW it would be the iBook.
With that being said, this time next year, after the Mactels (or whatever you want to call them) come out, my opinion will probably be to get the PB. But we'll just have to wait to see what happens.