One thing I'll note in regards to Microsoft patents is that for basically the entire lifetime of the company filing patents has been considered important. On t

One thing I'll note in regards to Microsoft patents is that for basically the entire lifetime of the company filing patents has been considered important. On the other hand, that doesn't necessarily mean Microsoft wants to keep them closed. On the Roslyn team we received a number of patents on some new algorithms and data structures to do fast and incremental parsing with immutable data structures. When Roslyn was open sourced all the code and patents went under Apache and are now open under its conditions.