I picked up my G1 at the Galleria in Cambridge (MA). The T-Mobile Kiosk was doing a brisk business and had plenty of people on hand to demo, sell, and activate the phone.
I've noticed a lack of advertising for the G1, but I read that T-Mobile will be starting TV ads soon. I wonder how much money Google is going to contribute to the campaign.
The phone is nice and works out of the box. I used it most of the afternoon and evening on the 3G network and used a lot of battery power. I'm still working on how to conserve (use EDGE only, no GPS, no WiFi). I particularly like the syncing of contacts which is helpful.