I lurk on this mailing list. Not high speed data per say, but some good info: http://wetnet.net/mailman/listinfo/seatcp
Keep an eye out for this radio sometime this fall/winter: http://nwdigitalradio.com/
There are a lot of reasons why Digital HS data isn't on the radar for most amateurs. One big reason is, other than voice and video, what do you do with it? Digital voice is OK, but is it all that much better than analog FM? Is there some big advantage to replacing repeater networks' analog links with digital repeaters and digital RF links? Most repeater ops are trying to get rid of RF linking, instead opting for Internet connections, due to the reliability and ease of setup. There's quite a few people who laugh at the DXers because of all the work that goes into a good HF station while they sit on the couch with an HT on the local IRLP node. While I disagree with them, I do see their point -if all they want to do is talk around the world why bother with all the other stuff (but of course that's not the point of DX now, is it).
Another issue is hardware. Not just the expense of Dstar and related tech, but other than connecting a PC or laptop to a dedicated modem there's really nothing out there. In the commercial world it took touchscreens like the iPhone and Android to get people to start using data for something other than simple texting. In the amateur world we don't even have T9 text input! I'm very excited that there's a growing community of ham app developers out there because if/when a manufacturer figures out how to strap an Android UI on an HT they'll be apps ready to go. If some such device got popular we'd see the networks get built out, much like when Kenwood put out the TM-D700 and D7 it made it easy for people to get into APRS. This led to software and other hardware to where we are now, with a mostly robust network.