First point: Full disclosure, I'm Canadian - in Canada it's not required to disclose your disability to prove discrimination. Generally you can at least get to the interview phase without disclosing. Not familiar with American law, didn't know that.

In Canada you are also required to have an elevator or ramp in every business building so stairs normally aren't an issue either. I don't think I've ever been to an interview where someone in a wheelchair wouldn't have access.

I agree disclosing in the interests of transparency is a great thing, I just don't see what it has to do with a cover letter and "Why you'd be a great fit".

Second point: I guess I hadn't thought that one through. :P