Microsoft has announced Open Source Interoperability Initiative. From the announcement press release :
The Open Source Interoperability Initiative exists to foster more open engagement between Microsoft and open source communities. It will encompass a broad range of facilities, events, and resources supporting interoperability, including labs, plug fests, technical content and opportunities for ongoing cooperative development. Microsoft plans to publish APIs and protocols that are used by Windows Vista (including the .NET Framework), Windows Server 2008, SQL Server 2008, Office 2007, Exchange Server 2007 and Office SharePoint Server 2007 -- as well as their future versions. Also Microsoft will not require developers to license or pay royalties for this information. Specifically, Microsoft is implementing four new interoperability principles and corresponding actions across its high-volume business products: (1) ensuring open connections; (2) promoting data portability; (3) enhancing support for industry standards; and (4) fostering more open engagement with customers and the industry, including open source communities.
Microsoft also agreed not to sue developers of open-source software and releasing tons of API. More information available at:
=> Microsoft Press Release