There was a recent Linux in the Ham Shack Podcast. In Episode #090 they interview John Hays, K7VE, of Northwest Digital Radio.
Here is a direct link to a MP3 of the podcast.
In the podcast; John gives us a better idea of what the radio is, and can be developed into.
A recent engineering update has been posted on the NW Digital Radio website, tells us that we can expect to get our hands on this one early next year if all goes according to plan.
As is, this radio seems to be in direct competition with the Icom ID-1. The ID-1 is over $1000 in price, and while this radio is a bit slower to move the bits, it's less harsh on the pocket book.
If you are looking for something faster than conventional data radios, yet more affordable than either the Icom ID-1 or UDR56K, then look at the Hope RF RFM12BP.
This is a half-watt, transceiver that covers 430.24 to 439.75 MHz, and supports data rates of 0.6 to 115.2 kbps. Priced less than $20.
Scott at Argent Data Systems says:
Programming them isn't the most friendly thing - There's no nonvolatile memory to store the configuration. We've got prototypes of an OpenTracker USB board with the RFM12BP - if you're looking for something easy to configure, that might be a possibility when we've got it ready.
John, G8BPQ has been playing with these modules and notes:
I looked at the higher powered (500 mw) RMF12BP, and ordered a couple for
experiments. But when I looked into the module in more detail I found it was
not compatible with the RFM22B, and is less flexible and more difficult to
program. I've since found the RFM23BP, which is a 1 watt unit that is
compatible with the RFM22B, so I've ordered a couple of them for testing,
and designed a board that will take either the 22B or the 23BP. Although it
is primarily intended for use with the Raspberry PI, it will also have an async port,
so it can be used as a standalone KISS TNC/Radio.