Are there any license restrictions to using FeedSync?
Microsoft has released the FeedSync specification under the Creative Commons license. This license lets others remix, tweak, and build upon the specification even for commercial reasons, as long as they credit Microsoft, and license changed specifications under the same terms. Read this for more information about the Creative Commons license. There is a separate patent promise called the Microsoft Open Specification Promise available to parties interested in implementing software that conforms to the FeedSync specification. This patent promise is available here.