I pulled the sim from my G1 yesterday and did a network search on my TM506. I can't register on it yet, but it is coming! I hadn't checked for a few weeks so I don't know when exactly it started showing up. I can't wait! This is in Broad Ripple by the way.
I'm told, and I've read some listed posted on a few different message boards that'll I'll be getting it here (Pittsburgh PA) in Q4 of this year. So I guess that means anywhere from Ocbober too December 31st. I'm really hoping it comes sooner.
It's up (and down) in Indy today! I blogged the news here: Indianapolis gets T-Mobile 3G! | Jaxidian Update