Microsoft will covenant not to sue open source developers for development and non-commercial distribution of implementations of these Open Protocols.
FLOSS developers and users used to be communists in the eyes of the Redmond giant, but now we are all one big happy family.
I notice that the list of products to which these principles apply it fairly limited ("Windows Vista including the .NET Framework, Windows Server 2008, SQL Server 2008, Office 2007, Exchange 2007, and Office SharePoint Server 2007")
Let's also see what 'non-commercial distribution' means...
Updated 25/Feb/08 -- Groklaw is not impressed either.