T-Mobile has begun its “official” if we can use that term loosely promotion of an upcoming mystery device that will run on its HSPA+ service. Now a bevy of devices are already available that can access this network, but none of which take full advantage of the promoted speeds. Going back to the first week of July, an unnamed T-Mobile spokesperson speaking to LightReading discussed that an HSPA+ handset would be forthcoming in September. Inside yesterdays T-Mobile press release regarding a number of HSPA+ city launches, was a single line regarding this future handset and was the first “official” word we’ve heard of its existence. “And later this summer, T-Mobile will unveil its first HSPA+-capable smartphone. More details will be available in the coming weeks.”

Come this afternoon, @TMobile_USA via Twitter states the above seen image, also alluding to a forthcoming device. So what do we think it is? The previously leaked roadmap highlights a September T-Mobile launch of the HTC Vanguard, aka the HTC Vision which we believe is a semi-follow up to the G1. Our sources peg this upcoming device as codename “Blaze” and we suspect thats an internal codename for the upcoming September launch.Would we go so far as to call this a G1 successor? Not so much, but its worth nothing that sources have pegged it as such. Of course all this is speculation and while we’re confident we’ll know in the coming weeks just what exactly is coming, in the meantime, its fun to guess!