A couple of weeks ago Google announced their WebM project, which provided a free software implementation of their VP8 video codec and a license to exercise the patents the company held on the software. (This after we appealed to them to do just that a couple of months prior.) The license they chose was unambiguously free: a three-clause BSD license combined with a patent license based on one found in the Apache License 2.0. Unfortunately, the interaction between the copyright license and the patent license made the result GPL-incompatible