Brazilian amateur radio operator PU2VLW has written a post (in Portugese) detailing how to use DSD version 1.7 to decode amateur radio D-STAR digital voice transmissions. (Google translate may be helpful.) DSD can be downloaded as source from GitHub.
His setup uses a Windows machine running SDR# to receive the D-STAR signal using an RTL-SDR dongle, and uses a physical audio out cable to connect the Windows PC’s audio out to the Ubuntu 10.04 box running DSD 1.7.
Here’s a related post detailing how to get DSD 1.7 up and running entirely on Windows.