In order to use the iPhone 4 on T-Mobile you have to jailbreak it, unlock it and then annoyingly cut your fatty SIM into a Micro SIM. Annoying! T-Mobile is making it a little easier by giving Micro SIMs to their customers.
T-Mobile has got no qualms about targeting the iPhone 4 with these free Micro SIMs either. In the product description it says:
Already have a GSM phone or iPhone that you need to activate-or have an unlocked GSM phone you want to use on the T-Mobile network? Just get a Micro SIM card and choose a plan.
It's a funny move for T-Mobile—one that clearly acknowledges that a ton of people use the iPhone 4 or iPad 3G on their network—but also sort of makes sense, they don't care what phone you use as long as you're using T-Mobile data. Might as well make it easy for everybody! Remember though, when you use the iPhone 4 on T-Mobile you won't get the three gees. [T-Mobile via MacRumors]