How effective is Javascript with screen readers, though? It's been a while since I played with a screen reader (late 2009 or so), but when I did even really simple things like a pop-up div confused it. It didn't inform the user that something new was being rendered or anything.
Surprisingly effective. A colleague of mine published some techniques to add consistency to Javascript events across screen readers: https://github.com/ryanfitzer/Accessibility
