The rubberized case seems like it would be a great idea, but how well does it slide into a pocket?

When I was playing with it in person, it fit into my pocket just fine. Plus, the key feel was surprisingly good.

What carrier are you on? Some are currently rolling out 850mhz gsm

I'm on T-Mobile, whose U.S. network is 1900MHz. AT&T Wireless and Cingular are deploying 850MHz. If I didn't need to replace my dying phone now, I'd wait for one of the new quad-band phones to come out.

The SonyEricsson phones look fantastic in theory, but I've read a lot of grousing about the poor quality of radio reception. I've been told that my T39m is much better than the T68i or later phones. If that's true, the new ones must be just awful. Also, before I owned the T39m, my previous phones were all Nokia, and I miss the fast, responsive Nokia UI.