A List Apart: Articles: The Inclusion Principle
http://www.alistapart.com/articles/the-inclusion-principle/

Accessibility is commonly touted via some text and a small hyperlink that leads to Section 508 at the bottom of a web page, a practice which upholds the spirit of the law. It usually reads something like this: “We are committed to making our site accessible and continue to test and modify the site for accessibility. Please do not hesitate to contact us if you have any problems accessing any of our content.” Some quick accessibility checks reveal that many site owners and developers consider the second part of that statement a convenient “get out of jail free” card. Developers sometimes think that using standards-based development principles, separating presentation and behavior via external CSS and DOM-based scripting techniques, and applying alt attributes to images creates Section 508 compliance. They don’t want to spend more effort on accessibility until they get feedback from users who have problems with the site.

"In universal design, perceived affordance—that is, the implicit understanding of how to interact with an object—actually coincides with the user’s ability to execute the action. Universal design is, therefore, inherently accessible." - yes!