I've been talking to more people about FeedSync since I posted the v1 specification earlier this month. One common question people ask is about licensing terms for the spec, and what our thoughts are about FeedSync implementations.
We've always made it very clear that our goal is to have lots of independent implementations of FeedSync, and that we want to enable royalty-free use of the specification. The spec itself is released under a Creative Commons license; today we're also making the spec available under the Microsoft Open Specification Promise. The full details are in this post on the FeedSync news blog. The short version is that the OSP makes life very easy for implementers. By placing the FeedSync spec under the OSP we're saying even more clearly that developers have royalty free use of the spec, now and in the future.
If you're new to the Open Specification Promise, they have a great page with an FAQ that explains the program in detail: http://www.microsoft.com/interop/osp/default.aspx. The Feedback from Representatives of the Community link shows the response from several people in the open source community; it's been very positive. You can also take a look at our FeedSync FAQ for some specific questions and answers about FeedSync and OSP.
It's great to have an existing program like OSP that is such a good fit for FeedSync, and I've really appreciated the support from the folks in the Microsoft Interop group in bringing the FeedSync specification under the Open Specification Promise.