From Microsoft: C# and CLI under the Community Promise
First the big news: Microsoft will be applying the Community Promise patent licensing to both C# and the CLI.
The announcement was done by Peter Galli at Microsoft over at Port25 and it states:
I have some good news to announce: Microsoft will be applying the Community Promise to the ECMA 334 and ECMA 335 specs.
ECMA 334 specifies the form and establishes the interpretation of programs written in the C# programming language, while the ECMA 335 standard defines the Common Language Infrastructure (CLI) in which applications written in multiple high-level languages can be executed in different system environments without the need to rewrite those applications to take into consideration the unique characteristics of those environments.
"The Community Promise is an excellent vehicle and, in this situation, ensures the best balance of interoperability and flexibility for developers," Scott Guthrie, the Corporate Vice President for the .Net Developer Platform, told me July 6.
It is important to note that, under the Community Promise, anyone can freely implement these specifications with their technology, code, and solutions.
You do not need to sign a license agreement, or otherwise communicate to Microsoft how you will implement the specifications.