Adam,
The idea is to be able to get everyone's thoughts on topics, not just the author. That's how discussion works. I have an opinion. If the subject was addressed to the author of the week, that implies you aren't interested in hearing my thoughts.
I assume the DDA is the Disability Discrimination Act in the UK. I don't have any experience with it, but I do have with Section 508 which is the US equivalent. I'm using the
word "accessibility" instead of DDA or 508 specifically. There's really a few layers to this:
1) JS and accessibility - Many forms of JavaScript can be accessible. Form validation/enabling/disabling is a very basic one. I remember in the early days of 508 use, we had debates about whether JavaScript was inherently non-compliant. (The answer was that of course you can use JavaScript. Screenreaders can handle it.)
2) DHTML and accessibility - Some types of DHTML are more accessible than others. A common
test is to turn off CSS and see what you get. Screenreaders are getting better at handling DHTML.
3) AJAX and accessibility - I can't wait! AJAX done right can make a page more accessible than having to keep reloading the page. ARIA is a standard that will provide a way of informing screenreaders that parts of the page have changed. It's an "evolving standard" so whether AJAX pages are currently accessible is a subject for debate. And since laws vary buy country, whether it is accessible yet turns into a question for lawyers.