Well, I broke down and bought one of the new iMacs.
First impressions are that even without the L3 cache, it's faster than my Powerbook, but then again, the iMac is at 1 GHz and my Powerbook is at 667.
The mouse is going to have to go. Not only is one button useless for me, but it sucks to boot. Too easy to accidentally click on things. I'll probably hook up a trackball since I have limited space there. I've already added another stick of RAM bringing it up to 512MB.
It's a great looking machine, it runs very quickly and the interface doesn't lag at all. My 667 runs it fine too, but I've seen how it can drag on a 500MHz machine.
Here's some pictures:
http://homepage.mac.com/thresher/PhotoAlbum19.html