I personally love my 12 inch PowerBook. It's a Rev D that I bought in the spring of 2005. It's hooked up to my 23 inch ACD and runs Photoshop, Dreamweaver, iMovie, etc. when I need it to. And the small footprint is just amazing.
However, I would love to upgrade. The 1.25 GB of RAM just isn't enough sometimes, and I would love my machine to FLY. The battery lasts about 2 hours...maybe.
I keep going to the Apple Store looking at the new models, wanting to upgrade, but nothing at the moment beats my PB. I really hate the look of the MacBooks and I have never enjoyed using any of my friends'. The trackpad is TOO big and somewhat unresponsive, the keyboard looks cartoon-y, and I miss having a latch.
What about the MacBook Pro? Well, I do love it, but I am waiting for all my apps to go Universal before I make that purchase, or at least until Leopard comes out. Still, I wish they made a 12 inch model.
At the moment, nothing beats it!