AT&T scores for $30 unlimited data plans on 3G-capable iPad, locked via Micro SIM

However, the idea of iPad as an unlocked device is not assumed to be like a normal unlocked mobile phones, it is just incompatible with its new “micro SIM”. It was a much smaller SIM also called 3FF SIM, this card was developed by the ETSI (European Telecommunications Standards Institute) to offer things like more storage space on-chip for provider applications, increased control and security functions and the new smaller form factor allows it to fit in tiny devices.

I think it was a craft from AT&T ditching the software lock( just like what on the iPhone), since it is possible to be hacked or unlocked while with Micro SIM it will be harder to find provider with compatible SIM card. But considering Micro SIM is a Standard, we just need some time for it to be pushed implemented, for the meantime we can expect just AT&T for this, oh I hear T-Mobile will be implementing this also.