Operating system: Windows Mobile® 6.5.3
So, that might imply Windows Mobile 6.5.3 is now official. Exchange-wise nothing changed; changes are mainly UI focused or under the hood. These include capacitive touchscreen support, multi-touch, touch controls (bye stylus), consistency, horizontal scroll bar instead of tabs, magnifier, Start Menu drag & drop, increased browser performance (IE), improved memory management, smoothed pan & flick gestures and speed improved zoom & rotation speed. It also contains updated runtime tools (.NET CF 3.5 and SQL CE 3.1) as well as Arabic read/write document support.
Also, it seems Sony Ericsson licensed SPB Mobile Shell as both Pro and Lifestyle models contain SPB Mobile Shell 3.0. Apparantly plain Windows Mobile isn’t appealing enough; Sony uses SPB Mobile Shell and HTC has HTC Sense UI.