Can't say we're surprised, but AT&T has confirmed to us that the PlayStation Vita 3G will indeed be carrier-locked. Only Ma Bell's SIM cards will work; inserting a SIM from T-Mobile or an international carrier will not work. We spoke earlier with Glenn Lurie, AT&T's Embedded Device President, who estimated that the company first received Vita units for testing around four or five months ago and worked closely with Sony even before that on the 3G modules and connectivity rules in the SDK, which helps expedite certification and avoid apps that could potentially harm the network.