Open Source Developers - this is great news for you!

Microsoft's Open Specification Promise (OSP) grants royalty free access to patents on specific technologies to implementers. Open XML is one of the (many) technologies included in this list.

This means that if you intend to implement Open XML in your application, any relevant patents inside Open XML are available to you completely free of charge. Free. Gratis. Without hindrance or obstacle. In fact, you don't even need to reference Microsoft in your application.

Sounds great right? Even so, some people weren't satisfied, and raised the issue that the OSP only covered the current version of the standard, and that Microsoft would consider coverage of future versions on a case by case basis.

Well, those hardworking folks in Redmond have modified the OSP so that it covers all future versions of the standard, on the condition that Microsoft is involved in the evolution.

'Involved in', not 'In control of'. :)

This means that royalty-free access to the patents in Open XML will be a permanent feature of this specification. It keeps getting better and better.