The iPad 2 Wi-Fi & 3G model from AT&T is actually unlocked and works with UK data plans, as tested by PC Advisor's sister magazine Macworld UK.
The situtation was expected (after all, the original iPad was also unlocked) but will come as a relief to customers looking to pick up an iPad 2 from a visit to the States, or by purchasing one and having it delivered to the UK. The iPad 2 is shipped with an AT&T MicroSIM card, but removing this and inserting a UK MicroSIM also provides a data connection.
Macworld tested the iPad 2 with a MicroSIM card from Three, and the data connection worked fine.
Potential customers should be careful to buy an AT&T iPad 2 model, and not a Verizon iPad 2. The AT&T model comes with a MicroSIM card which can be swapped for a UK MicroSIM card. Verizon, however, does not use SIM card technology and there is no way to get a data connection from a Verizon iPad 2. So be sure to get the AT&T model (or a Wi-Fi only unit).
The AT&T card from an iPad 2 Wi-Fi & 3G can be replaced with a UK MicroSIM card for mobile data connection.
At the top left you can see the 3 symbol, which shows that the data connection is being provided by the Three network.