The T-Mobile G1 ("iPhone killer") had started shipping just 2 days ago and its already unlocked !! Yes, its unlocked before the iPhone 3G which was released months ago...
In case, any of you have got a G1 or have switched from the iPhone, heres how to quickly unlock your Android phone:
NOTE: You must have one already activated T-Mobile sim card to do this.
1. Go through setup process to link any Gmail account
2. Go to Settings > Wireless Controls > Wi-Fi Settings > Enable Wi-Fi
3. Look for a Wi-Fi network around you
4. Remove the original sim card and replace with your new unactivated sim card that came with your phone
That's all you need to do in order to get the G1 up and running without having to tie yourself down to a 2-year contract.