Word has leaked that T-Mobile will be offering Windows Mobile 6 Smartphone Edition as a downloadable upgrade to Dash owners starting Friday, May 4. Presumably new Dashes will begin shipping with WM 6 installed on or around the same date.
Can't wait that long? There may be a link floating around the Web enabling you to download the official (non-Beta) release a few days early. I'm not advocating your doing so, nor am I saying that attempting to download and install the update won't fry your phone. All I'm saying is I might have read a forum post or two containing a link to what's supposedly the same update that T-Mobile will make available on the 4th.
Additionally, photos and a video of the forthcoming T-Mobile Wing (though it may not be called that, after all) have surfaced online. This HTC-made successor to the T-Mobile MDA will also run Windows Mobile 6 (the Pocket PC version) and feature WiFi, a QVGA touchscreen, slideout QWERTY board, and 2 mp camera. Wing, Atlas (HTC's name), or whatever T-Mobile winds up calling it ... it'll be 17mm thick, myFaves compatible, and supposedly showing up on T-Mob May 21st.