This just in from Twitter, The OSI has approved MS-PL and the MS-RL (Microsoft Reciprocal License) as valid open-source licenses. Woo hoo! We've been saying our stuff on CodePlex is open-source for a while. Nice to now have it be official! This is actually awesome and means we are making good progress in building bridges to the OS community. As a former member of that community, I am thrilled. Great work MSFT!