That seems to be incorrect. We have problem children in us-east-1b, -1c, and -1d.
If multiple AZs are down, AWS are going to have some serious explaining to do...
Interesting. This is news to me.
I found some more info here (Google cache since alestic.com is presently unreachable): http://webcache.googleusercontent.com/search?q=cache:0jxzyFj...