I really enjoyed this podcast discussion at ShopTalk with Derek Featherstone: http://shoptalkshow.com/episodes/058...-featherstone/

I think it gives a really clear overview of what's involved with accessibility, the issues with screen readers and other assistive devices, and pros and cons of various coding practices like lists inside <nav>, use of ARIA and certain CSS techniques like display: none and hiding elements off screen, CSS3 and responsive design.

An easy going but insightful intro.