Via John Palfrey:
Microsoft has just unveiled a new commitment not to assert certain rights against people who develop code based on specifications that Microsoft has developed. It’s called the Open Specification Promise.
There is a difference between (a) putting a certain type of liberal copyright on a specification of a protocol or file format and (b) allowing unencumbered implementations of such specification. Microsoft has acknowledged as much with their new Open Specification Promise.
An analogy might be if I publish a recipe for baking a cake under a Creative Commons license, you might still not be able to actually bake the cake because I have some kind of an patent, pending or otherwise, on implementations of the cake.