T-Mobile just sent out an invitation for an event on December 14th that it's co-hosting with Nokia. Something tells us this isn't for a Symbian device, which leads us to the conclusion that T-Mobile is likely going to be the first American carrier to launch one of Nokia's Windows Phone-powered handsets. What we don't know is which device (or devices) it will be; the Lumia 710 seems like a strong possibility since it's already found its way to Nokia's US site, but that's just speculation at this point. More on this as we get it.