Is the G1 shipped unlocked?

I’ve read that this is the first T-Mobile phone to be shipped unlocked. Is this true?

If that’s the case than spending $399 and activating it on AT&T would be worth it for some people. (Or activate for $179 and spend the $150 cancellation fee bringing the total to $329.)

Also, AT&T already has 3G Towers on in more areas than T-Mobile.

I would like to hear back from G1 owners on this. Have your buddy with an AT&T phone give you their SIM card, put the card in the G1, and see if you can make a call or surf the web.