Odiogo, which converts blog posts into MP3 files, makes content accessible to blind users. As Brian Friedlander notes, blog owners still have to go through the process of creating the files for users.
Screenreaders, of course, have been around for years, but they have a tough time keeping up with Web innovations. AJAX, for instance -- how do you describe a tag cloud? Or, worse, CAPTCHA, which requires users to correctly type text hidden in a box.
Innovations are created by those who don't need assistance, and new assistive technologies are then needed by the blind. It's a constant game of catch-up, and those who need help seem to keep falling further behind.
Can this be allowed under the ADA?