Rumors surrounding T-Mobile's very mysterious "Project Black" have been swirling around, and those in the know are claiming it's going to blast T-Mo out of fourth place in the carrier wars. What do we know about Project Black?

T-Mo News claims it's not a phone or a promotion, which suggests it might be some kind of coverage rollout—T-Mo certainly could use a more widespread network, since they've already got some sweet phones to take advantage of one. Apparently T-Mobile staff are being trained for an imminent release or rollout of Project Black starting this week, but again, we have no idea what this actually is (or if it even exists, really). Rumors have been bubbling from a couple different sources (Phone Arena and T-Mo News, mostly), so the rumor may have something real behind it, but we don't know much for sure yet. We'll keep you updated as soon as we figure out what this secret project actually is. [Electronista and T-Mo News]