Baker & McKenzie paper compares Microsoft's OSP with Sun & IBM's equivalents.
Leading international law firm, Baker & McKenzie, have posted an updated* paper entitled "Standardisation and Licensing of Microsoft’s Office Open XML File Formats":-
This paper was commissioned by Microsoft and seeks to address and clarify any misunderstandings in the industry, and among the wider general public, about both the standardisation process that Microsoft has embarked upon in respect of its Office Open XML Reference Schema, as well as the legal arrangements governing the use of the Schema by others.
The paper examines the terms of Microsoft's "Open Specification Promise", and compares with Sun Microsystems' OpenDocument Patent Statement, IBM's Interoperability Specification Pledge, and with standards licensing practices generally with regard to specific topics such as versions, partial implementations, necessary claims, optional portions, and referenced technologies.
As one might expect, there are a lot of similarities. The substantial similarities should help give people perspective regarding current industry practice.
*the original June 2006 paper, "Standardisation and Licensing of Microsoft’s Office Open XML Reference Schema" is still available here.