So far I found Garmin, Pro, Magellan, and Magellan's offshoot Mio branded cycling computers to work withe the wireless adapter. I've been thinking about getting a Garmin unit anyway so this will help push me over the edge, pardon the pun!

I had found an article that said Smartphone software would be available down the road to work with the Di2 but it was for recording data from the Garmin not reading live data from the Di2, I misinterpreted the info.