FYI - The next candidate release for WCAG 2.0 Web Content Accessibility has been released at
http://www.w3.org/TR/2008/CR-WCAG20-20080430/#guidelines
http://www.w3.org/QA/2008/04/wcag20_cr_april2008.html (FAQ)
This is an overhaul which is meant to address gaps in WCAG (e.g. more recommendations for audio) and make recommendations for new options (e.g. CAPTCHA, AJAX like interactive Web sites). For most purposes, level A is sufficient. Fortunately, a lot of the new guidelines have been suggested before as usability guidelines or were a part of WCAG 1.
It should be noted that Section 508 is currently being revised by TEITAC (http://teitac.org/wiki/TEITAC_Wiki), aka the Telecommunications and Electronic and Information Technology Advisory Committee/United States Access Board, and the revision will more closely match WCAG 2.0.
Since Penn State A.D. 54 currently refers to Section 508, I think a lot of us will be getting to know WCAG 2.0 very well indeed...