Interesting. I knew about the hardware differences but wasn't aware of the cell chip differences, if any. Obviously we have a first hand account of the device working on T-Mobile and the reviewer saying only ATT. I would have thought the European version would work on either T-Mobile or ATT's 3G network. The European versions are usually unlocked and allowing either of those when using them here. Maybe there is more than one European version with some being locked to the ATT frequencies, some to the T-Mobile ones and some entirely unlocked?