That's been possible since the release of iOS5 through a private API (which is sufficient for debugging): http://atnan.com/blog/2011/11/17/enabling-remote-debugging-v...

iOS6 makes the feature officially supported (though the API for webview-based apps is probably different, I haven't checked): http://taitems.tumblr.com/post/24936855546/what-ios-6-mobile...