Jeffrey Zeldman called it. His book Designing With Web Standards pointed out that inaccessibility might get you in trouble (if you haven't read it, I highly recommend that you do so). And just recently, a blind student sued Target for violating the Americans with Disabilities Act for providing an inaccessible website.
As much as I respect Target, and as much as I enjoy shopping there, I can only feel so sorry for them in this situation. Creating an accessible website is incredibly easy. To get it wrong, and subsequently discriminate your customers, is tragic. If you run a website, learn to incorporate accessibility into your design. Disabled users will thank you for it.