I'm not sure how relavent this is but we've done a lot of work on some aspects of OACS WRT the W3c accessibility guidelines http://www.w3.org/TR/WAI-WEBCONTENT/ . We have branched in these areas in any case as they were deprecated anyway before we started using them (old ticket tracker and old workflow) so the code may not be of use. The principles should apply in any area of openacs I guess. If the W3c accessibility guidelines are relavent I may be abe to help.
The DDA is pretty vague it simply states that an organistation must make 'Reasonable Adjustments' to allow access to those with disabilities. The Royal National Institute for the Blind has plenty of info here http://www.rnib.org.uk/xpedio/groups/public/documents/publicwebsite/public_dda.hcsp
Generally its ensuring that alternate technologies can navigate a site..
Was there a particular aspect of OpenACS to which your referring and is this the vanilla OpenACS distribution? I would have thought that as soon as people apply their own templates then it becomes their responsibility to adhere to the act.
I was asked this by a non profit intersted in OpenACS and they would be using stock .LRN. I don't think it would be a problem, but one never knows which is why I was asking. Will look at the materials you provided, thanks for your information!