My behavior is just like your's DJY, but that's when I'm at home. For us college students, the dorm rooms offer much less room to roam with a laptop while inside our residence. I can understand why someone would have gotten a laptop for college so they could easily carry it home and back. However, the new iMac looks perfect for the same application, and will give a more powerfull experience with a larger screen. For this particular user, I say go for the iMac.
Personally, my 12" Powerbook goes everywhere I go on campus. I still have a desktop setup in the room, an Intel machine in an Antec case with two 17" LCDs, a 5.1 Channel Logitech sound system, a TV antenna, various cradles for Clie, Karma, Mouse... etc. I can MOST-DEFF see the appeal of an all-in-one such as the iMac just for moving in/out, as breaking down and setting up my desktop can feel like quite a project. Not to mention packing the LCDs so they don't get damaged.