According to the an article on ArsTechnica the judge of the case ruled that APIs are not patent-able.

He referred to the structure of modules/methods/classes/functions as being like libraries/books/chapters. To patent an API would be putting a patent on thought itself. It's the internal implementations that really matter.

With that in mind, Mono (C# clone for Linux/Mac) has always been viewed tentatively because, even though C# and the CLI are ECMA standards, Microsoft holds a patent on the technology.

Microsoft holds a covenant not to sue open source developers based on their patents but has maintained the ability to pull the plug on the Mono development team if they felt the project was a threat.

With the recent ruling, is Mono finally out of the woods. A firm precedent has been established that patents can't be applied to APIs. From what I understand, none of the Mono implementation is copied verbatim, only the API structure and functionality.

It's a topic I have been personally interested in for years now as I have spent a lot of time developing cross-platform C# libraries in MonoDevelop.

I acknowledge that this is a controversial topic, if you have opinions that's what commenting is for. Try to keep the answers factual and based on established sources.