An image of what appears to be a roadmap for upcoming T-Mobile USA devices has surfaced online and it contains details about the company's upcoming Android handsets.

The details were posted by an anonymous blogger on the TMOToday.com website and purports to show the planned US release dates for several upcoming handsets.

According to the roadmap the next handset to hit the market will be the HTC Sapphire/G2 which is rumoured to be in for a name change before launch in the US this summer. Incidentally this seems to coincide with the company's plans to transition 3G to all markets during this period too.

Hot on it's heels is a previously unseen second Google Android powered device called the G1v2 but we're hoping that by the time it makes it to market it will be better known by its codename which is the far more satisfying Bigfoot.

There are no spec details on the image but the handset appears to have a non edge-to-edge touchscreen display and a horizontal sliding Qwerty keyboard.

Also set to launch during the same period, namely September to November 2009, is the Samsung Houdini.

There is some speculation that the Houdini's resemblance to the recently announced Samsung I7500 is more than just coincidence and that it may in fact be a US specific release of the handset, but right now we're not convinced.

If that is the case, you can check out our coverage of the Samsung I7500 including specs and pics.