Before you even get to whether the content of these sites is accessible, you need to get past the inaccessible elements of the sign-up process. All the Web 2.0 sites that were reviewed for this article require users to sign up, and all use a method called CAPTCHA (completely automated public Turing test to tell computers and humans apart) to verify that you are a human, not a computer. A CAPTCHA is a small graphic that contains text, numbers, or both. You are asked to type the characters that are displayed into a text field. CAPTCHAs are basically a Web 1.0 technology that is used to prevent automated systems, such as those used by spammers, from signing up for services. Unfortunately, because they are graphic, CAPTCHAs are completely inaccessible. Some CAPTCHAs include an audio alternative, but because of voice-recognition technology, the quality of the audio is poor on purpose. Anyone with less-than-perfect hearing or with auditory-processing problems would find them difficult to use.

RIA accessibility is very much a work in progress, but one thing is clear. It will be extremely difficult to provide any kind of backward compatibility for RIA web sites. Old versions of screen readers simply will not work with the new technology, but neither will old versions of web browsers.