What truly defines accessibility?

I’ve written before about what truly defines accessibility.

Recently this question was raised in the form of a complaint filed by the National Federation of the Blind and the American Council of the Blind, along with an Arizona State University student who is blind to the Department of Justice (DOJ) that use of the Kindle devices discriminates against students who are blind or visually impaired. A daily dose of postings from The Chronicle's technology blog (( ... 01.15.10)

I have a Kindle and it does have a feature that reads the book to me. Unfortunately, it does not verbally navigate the buttons on the device. The DOJ said that without access to the menus, students who are blind have no way to know which book they have selected or how to access the Kindle DX Web browser or its other functions yet the technology to make navigational controls or menu selections accessible by blind users is available.

This upsets me greatly because my book, DIVE IN, is now available on the Kindle. The initial thought was by making DIVE IN available on the device, it would provide everyone with access to the book. Once again, when is accessibility truly accessible?