The Adaptive Technology Resource Center (ATRS) released a list of issues which have been raised in their analysis of the OOXML specification with regard to accessibility.
According to the paper, the standard itself contains a number of questionable regulations which might pose a threat to the ability of the programmer to make the implementing software accessible to disabled people. The main point of criticism is that some proprietary formats have been used in areas where free W3C standards are already in existence and covering the same functionality. However, while the W3C standards have been developed with accessibility in mind, the notion of accessibility is apparently missing entirely from the OOXML standard.
As an example, some of the specifications for insertion of images do not allow for image formats which permit access to disabled users. The ATRS then goes on to demand the revision of these issues. A long list of references to objections regarding accessibility and related issues is referenced at the end of the paper.
For more details about OOXML, visit the FFII Switzerland OOXML documentation.