Microsoft has claimed that 1'700 companies are demanding the standardization of OOXML urgently. Despite the fact that they haven't been able to produce any of these 1'700 companies in an ISO committee, there's one thing that makes me think:
A small Google search for OOXML files returns about 900 results. Looking closer at it, there are also things like a Wikipedia article on .docx files in the results, so after sorting it out you get about 700 OOXML documents.
Another Google search returns that roughly 200 of these documents actually come from Microsoft themselves. This means that these 1'700 documents can have authored about 500 public OOXML files.
How is that? Did ever 4 of them co-author one document?