You can see an unlocked iPhone using the T-Mobile network in this pic:
Ryan Block over at Engadget writes:
It’s high noon, Apple and AT&T — we really hate to break it to you, but the jig is up. Last night the impossible was made possible: right in front of our very eyes we witnessed a full SIM unlock of our iPhone with a small piece of software. It’s all over, guys.
He also confirms that:
we can confirm with 100% certainty that iPhoneSIMfree.com’s software solution completely SIM unlocks the iPhone, is restore-resistant, and should make the iPhone fully functional for users outside of the US.
Head over to Engadget to read details, see more pics and watch a video on how to unlock your own iPhone.