A lot of noise is being generated out of Microsoft's announcement that it would 'open' an Outlook format, which some Free software like Thunderbird was already able to decipher anyway. Microsoft did something similar with proprietary Office formats that developers had already reverse-engineered due to Bill Gates' brutally anti-competitive attitude.
However, in other cases (in fact most of the cases), the Microsoft-dominated WG4 appears to have overstepped the permissible bounds for corrigenda, and indeed gone far, far beyond what it stated it would be doing in corrigenda. Let's look at a few examples.
(Sadly, the general public is not given access to the text of the draft corrigenda (the DCOR) but those on the inside can follow along by reading N 1252 in the SC34 document repository.)
[...]
I invite you to go back to the defect log [PDF] and search for "BRM". You will find several oddities. For example, among these proposed changes are some that actually reverse BRM decisions. Yes, you heard me correctly. SC34/WG4, the Microsoft-dominated committee that maintains OOXML, is undoing various BRM decisions that enabled OOXML to be approved in the first place. Why? Well, of course, to make the standard conform more to Microsoft Office.
[...]
So although Microsoft Office does not conform to ISO/IEC 29500 today, I have no doubt that within a few months it will fully conform. But not a single line of code will have changed in the Office product. Office 2007 will be retroactively made to conform to ISO/IEC 29500. What will happen is the standard will be modified to match that single vendor's products, by misapplication of an ISO procedure intended for fixing minor drafting errors.
So why go through all this trouble? I believe this is all about getting the OOXML standard "corrected" so Microsoft can push for it to get it officially adopted around the world. The only reason they've held back so far is because MS Office does not actually implement ISO/IEC 29500 today. So it would have been counter productive for them to push for official adoption. However, once this oversight is remedied, by changing the standard to match their product, then watch out.
[...]
So Microsoft is now off extending OOXML, and this whole ISO escapade with OOXML seems for naught. (I hear also that Microsoft is also backing off the submission of their Extensible Page Specification (XPS) to ISO as well, saying that "an Ecma Standard is good enough".) It appears that Microsoft got what they wanted from ISO and is moving on. Who said it would last more than a night? As my grandmother used to say, "Why buy the cow when you can get the milk for free?"
[...]
The pattern is clear: OOXML will be extended by Microsoft much faster than it will be standardized and corrected by ISO. This will make the ISO version of OOXML, currently not supported by Microsoft, even more irrelevant in the future.
"This year WG1 have had another major development that has made it almost impossible to continue with our work within ISO. The influx of P members whose only interest is the fast-tracking of ECMA 376 as ISO 29500 has led to the failure of a number of key ballots. Though P members are required to vote, 50% of our current members, and some 66% of our new members, blatantly ignore this rule despite weekly email reminders and reminders on our website. As ISO require at least 50% of P members to vote before they start to count the votes we have had to reballot standards that should have been passed and completed their publication stages at Kyoto. This delay will mean that these standards will appear on the list of WG1 standards that have not been produced within the time limits set by ISO, despite our best efforts.
The disparity of rules for PAS, Fast-Track and ISO committee generated standards is fast making ISO a laughing stock in IT circles. The days of open standards development are fast disappearing. Instead we are getting “standardization by corporation”, something I have been fighting against for the 20 years I have served on ISO committees. I am glad to be retiring before the situation becomes impossible. I wish my colleagues every success for their future efforts, which I sincerely hope will not prove to be as wasted as I fear they could be."
--Martin Bryan, Former Convenor of ISO/IEC JTC1/SC34 [OOXML] WG1