It's easy to see how this came about; A story appeared on The Reg yesterday regarding the Sense UI (based upon the UI of the same name from the Android handsets) would be appearing on the HTC Touch HD2. It's T-Mobile not understanding that UI != OS.
Oh, and do me a favour; Hold your hands out in front of you, palms forward, fingers together, and thumb at 90 degrees (or as close as you can get it) to your hand. The one which forms a shape like an L with the index and thumb is your *left* hand. Incidentally, that's where you'll find the Start menu on WinMobile.