Yeah, the links in the wild are the problem. Users have a habit of copying URLs from the URL bar, unfortunately.

I think Google could have done this better; they could have made it so all ajax URLs are crawlable (standard robots rules apply) as long as your site opts in, then you'd only have to support pretty URLs, something you probably have to do anyway.

For example, now twitter needs to support twitter.com/#!/ev and twitter.com/ev and twitter.com/?_escaped_fragment_=ev