Microsoft has long used its superior support for the assistive technology community to help maintain its market dominance.
The Massachusetts plan to offer ODF as a single file standard was thwarted, in large part, by opposition from groups requiring assistive technology. Peter Korn of Sun has an extensive blog post about it, with all the background.
What's interesting here is the use of open source. The Daisy plug-in will be hosted at Sourceforge. But it only seems to support the latest versions of Office.
So this is not only a big loss for ODF, until Open Office responds, but a big incentive for blind and dyslexic users to upgrade to the latest version of Office.
OASIS, however, has a draft of a ODF-to-Daisy converter online, so it's not like the open source community is completely blind in this matter.
Still, all this reinforces the need for groups like OpenOffice to have ample funding, as Mozilla does, so they can respond to these kinds of challenges.
It will help against Microsoft, but it will also help those in need.