GameStop Mobile launches as AT&T virtual carrier, gives us rare bring-your-own GSM in US (update)

Here's an expansion of mobile competition in the US that comes out of left field, even for us: GameStop as a cellular provider. GameStop Mobile, as it's called, is that rare bird of an AT&T-based MVNO that relies on a bring-your-own-device strategy. As long as your hardware works on AT&T's 850MHz and 1,900MHz bands and isn't locked to another carrier, you can bring any GSM- and HSPA-based phone (or data-only device) and use it contract-free: rates start at anything from a strictly pay-as-you-go $5 through to a $55 monthly plan with unlimited voice and text, if just an anemic 500MB of data. Tablet owners and other data-only fans can pay the same $55 for 1GB per month -- a bit stiff considering that those on AT&T proper can get 5GB of data for slightly less. No doubt this is to take advantage of iPad and iPhone trade-ins, PlayStation Vitas and the overall rise of unlocked devices. We're just wondering whether GameStop will catch a few customers subscribing as they pick up their Diablo III pre-orders or else face the uncertain future that befalls many MVNOs.

Update: As our friends at Joystiq have pointed out, the GameStop Mobile website is no longer publicly accessible. Looks like someone may have pulled the switch a bit too early.