I have finally bitten the bullet and plan to transition over to a Windows Mobile phone from my current Sony Ericsson (I have a P910i). The HTC Hermes is the phone I would be moving to, the ability to get email on the fly (blackberry style) is the main motivation. HTC Hermes (also know as i-mate JASJAM) is going to be released in a about 2-3 months and is ideal for my needs. You can read a review of this phone here.
So if in 2-3 months any of you interested in a Sony Ericsson P910i, then let me know – it would go cheap :).