While T-Mobile may not yet be an official iPhone wireless carrier, they’re looking to make what money they can off the iPhone.

Per Engadget, T-Mobile has thrown caution to the wind and is offering unlocked iPhone 4S units into stores, customers being able to sign up for the carrier’s US$70-a-month (amongst others) unlimited plan anyway.

From September 12th, iPhone 4S display units will be rolled out in stores, with helpful sales staff around to swap out your AT&T microSIM for one of its own. You’ll also be able to get hold of network-specific apps like myAccount, Visual Voicemail and T-Mobile TV as soon as they’re ready. In order to make this marvel possible, it’s rolling out 1900MHz HSPA+ access to allow customers access to its wireless service.

Stay tuned for additional details as they become available.