A Dwarf Priest has a nice long post up about the relationship between Blizzard and one of the more hidden (and yet surprisingly large) groups within their population: disabled gamers. It's no secret to anyone who's played WoW for a while that a lot of disabled gamers have found a lot of solace in a social game where you can be almost completely anonymous and play a character at whatever pace you want to play. Even if you go with the lowest of estimations, there are about 525,000 people playing the game with some kind of disability in real life. That's a much bigger number than I expected, and it's a significant number of people paying Blizzard every month.
Fortunately, Dwarf Priest found that accessibility is relatively good in Blizzard's game -- most of the work is actually done with third-party addons, but the UI and display is so customizable that even with the default interface, many people without a full range of controls or movement can figure out how to play the game. For their part, Blizzard has agreed that a customizable UI is the best way to make a game accessible -- J. Allen Brack says that's a priority in this interview with Able Gamers.
Dwarf Priest has lots more, including a quick comparison with accessibility in Warhammer Online, and even a weird wrinkle in the Glider lawsuit (the botting program's creators are apparently claiming it helps disabled players play their characters). It's a very well-written post about a subject that doesn't get covered much, and there's lots of extra reading to dig into at the bottom as well.