T-Mobile USA has gone on record in stating that its network is now home to more than 1 million unlocked Apple iPhones. While the figure is not incredibly surprising considering the massive popularity of Apple’s smartphone line, it certainly reaffirms the fact that T-Mobile subscribers are itching for an iOS option. Though the overwhelming bulk of iPhones being used on T-Mobile’s network are 3G and 3GS models, unnamed T-Mobile spokespeople also confirmed that the carrier has micro-SIMs in development. For the time being, iPhone 4 owners who want to use their devices on T-Mobile’s network have to perform a bit of surgery on their T-Mobile SIM cards. Of course, we doubt the carrier would adopt micro-SIM cards without actually selling a device that can make use of them, so this little snippet may add a bit more credence to rumors of a T-Mobile-ready iPhone 5 that may launch in August or September.