Codec2 Open Source Vocoder Project
David Rowe, VK5DGR, is working on Codec2, an open source low rate speech codec that is intended to replace the proprietary AMBE vocoder in D-STAR. Bruce Perens, K6BP, discusses the Codec2 project here, and further information from VK5DGR is here.
If you missed it, I discussed the issues with proprietary technology and D-STAR here, here, and here.
If you believe open source technologies are crucial to amateur radio, please donate to the Codec 2 project. Paypal donations are accepted.