Great article!
One thing I might add. Currently here in the US it is "recommended" that all organizations that receive federal funding of any sort follow the Section 504 guidelines, which can be met by following section 508. If past behavior is to be repeated this usually precedes a guideline being made into a requirement. Not following the accessibility guidelines could at some near future point in time cost you your federal funding, and since no one likes being "under the gun" and stressed to get something done, wouldn't it make more sense to do it now and forego that possible future threat? This is already the law in Great Britain, Austria, and probably a few other countries. It will someday be the law in the US.
Some additional links for anyone interested:
Bobby Accessibility Tool
Cynthia Says Portal
Section 508
Refreshing Regions
The CSS-Discuss List
Standards/CSS Friendly Web Applications
Just for the record, my sites came up better than most, since they meet current web standards, but I still have a bit of work to do!