That would just happen to be our own joedolson, Cre8 Moderator.
If you want to know 'why?' before tackling the 'how?' of WCAG 2.0 this series reads really well.
Note: if you already know 'how' learning 'why' is still quite useful.
This first article tackles that first principle of 'is it perceivable?'.
The new web content accessibility guidelines are designed around four fundamental principles:
1. Is it perceivable?
2. Is it operable?
3. Is it understandable?
4. Is it robust?