Twitter OAuth definitely needs to be renamed Twitter Connect. If you don't have a Tipjoy account, check out how easy the signup is by going to http://tipjoy.com/ and clicking the Twitter banner.

That's just so ridiculously easy, it should be highlighted by twitter. They're a bit distracted I guess with their meteoric growth to market this properly.

I think the problem is that OAuth isn't usually touted as a sign-on standard, only an "access API info" standard. With a couple tiny tweaks OAuth could be a standard that allows for this kind of "Connect" protocol for any web application.

Specifically, all that would need to happen to make this perfect is for OAuth requests for a user that already have an access token automatically push through to the callback phase instead of requiring a "re-allow" of the client's services. This wouldn't conflict with the OAuth spec in any way that I'm aware of.

Looks great! One suggestion though: it'd be nicer if the plugin used module mixins rather than class inheritance to decorate the User model with your TwitterAuth functionality.