"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
T-Mobile USA Launches iPhone, Rolls Out New TV Ad
TechCrunch notes that some T-Mobile retail stores are seeing small lines this morning as customers seek to purchase the device using under T-Mobile's new "Uncarrier" service plans which begin at $50/month with no contract. The business model separates the device and service costs, putting the full unsubsidized device cost onto a separate 24-month payment plan.
As noted by TmoNews, T-Mobile has also rolled out a new television ad for the iPhone, touting the pairing of the popular device with T-Mobile's network and service plans.
It's the phone that's revolutionizing phones. Make sure it's running on the carrier that's revolutionizing wireless. Introducing iPhone 5 on T-Mobile. With our advanced nationwide 4G network, and no more restrictive annual contracts required, only T-Mobile lets your iPhone 5 be as great as an iPhone 5.