It is also widely believed that Apple isn't thrilled with ATT at this year's WWDC and the absence of ATT, the booing of ATT, and the negative blogs directed at ATT was largely due to its inability to support all iPhone 3.0 features from day one. I have also indicated that Apple can perceive this as a breach of contract if allowed and begin to look elsewhere for a second partner in the US. The obvious being T-Mobile.
MacNN is reporting T-Mobile will begin to offer the iPhone 3G in the UK in a few months. There is no mention of the iPhone 3GS as they've noted. Previously, Orange was the exclusive iPhone provider. Perhaps this is a realignment by Apple across the pond by playing off two players for more money or a simple desire to expand the pool of buyers. We'll know once those "in the know" start to talk.
In the US, with a tweak of 3G chip, Apple can easily bring the iPhone 3G to T-Mobile for a short time at $99 or even $199 to punish ATT or simply to exert pressure on Verizon and ATT in future negotiations.
The only thing that is going to prevent such a deal from happen is T-Mobile's 3G coverage. But hey, it's the iPhone. Who cares, right?
Note: This is not a rumor and I have no secret knowledge of Apple's plans. I'm simply speculating based on what I know about Apple's past behavior. For instance, once Apple dropped ATI in favor of Nvidia because ATI made the stupid mistake of preempting an Apple product announcement. So don't be surprised if Apple sucker-punches ATT for not keeping up with the times.