T-Mobile, HTC, and Microsoft collaborated on the Neo interface introduced on the T-Mobile version. The interface was designed to allow a more familiar cell phone user interface on a smartphone.[1]
Shadow 2009
T-Mobile replaced the original Shadow model with a newer one in early 2009. In addition to a design facelift and new colors, it supports Unlicensed Mobile Access through the T-Mobile @Home service. It will also have Windows Mobile 6.1 Standard installed. [2]