Wojciech Kaczmarski (SP5WWP) and his team have been working on the M17 open source digital radio project:
Open source handheld for a novel digital communication standard called M17.
The goal here is to kick the proprietary protocols off the airwaves. To do that, it’s not just good enough to be open, it has to be legitimately competitive.
See the full post on M17 Project web site.