Palm's Treo 750 is one of two models offered with Windows Mobile - this one in particular using 6. Specs include a 2.5" 240x240 touchscreen, 300MHz processor, miniSD support, 1.3MP camera with 2x zoom, 4-hour talk-time, GSM/UMTS support and more.
You can read Greg's full review here and discuss it here.
You can read Greg's full review here and discuss it here.