Microsoft has updated its Open Specification Promise page as of July 25, and it now says in the FAQ that the GPL is covered, including commercial:
Q: I am a developer/distributor/user of software that is licensed under the GPL, does the Open Specification Promise apply to me?

Industry standards may not be open (e.g., Microsoft Word file formats) so there are reverse-engineering risks with any OSS dependent upon those standards. The MoJ preference for open standards (e.g., Open Document Format, which is now supported even by Microsoft) lessens this risk.

There has been much discussion in the free software community and in the press about the inadequacy of Microsoft's Office Open XML (OOXML) as a standard, including good analysis of some of the shortcomings of Microsoft's Open Specification Promise (OSP), a promise that is supposed to protect projects from patent risk.

The day is fast approaching when the comment and voting period for ISO/IEC DIS 29500, the draft ISO specification based upon Microsoft's Office Open XML formats, will either be approved or not. As Sept. 2 comes closer, Microsoft appears to be stuffing the ballot boxes of some countries' ISO organizations while open-source and standard organizations are firing back with furious words.

This paper provides legal implications of formats and explains why it is better to adopt format based on open standards. Guidelines for implementing open formats are also provided.

In a resounding victory for Microsoft Corp., bills seeking to mandate the use of open document formats by government agencies have been defeated in five states, and only a much-watered-down version of such legislation was signed into law in a sixth state.

Microsoft front attacks FOSS in a new paper which IDG gives visibility to

Microsoft’s position is hardening as the ISO vote on OOXML (DIS 29500) in Geneva approaches at the end of this month. We know more clearly now how Microsoft and its proxy group, ECMA, will position Microsoft’s OOXML specification in advance of the vote. In short, Microsoft is betting that its influence with National Bodies will allow it to push through a specification which elevates its own interests over that of truly competitive, open international standards. In the end, it will be Microsoft’s own inflexibility that will be its undoing, and that undoing means knocking the OOXML out of approval for ISO status.

The Ballot Resolution Meeting to discuss the technical comments arising from the fast track process to have Microsoft’s Office Open XML formats accepted as an ISO standard was held last week in Geneva.