warden

How can I use devise's "warden" to authenticate a rack app in the same stack as the rails app that uses devise ?

By the way, I'm using rails 3. How can I use devise's "warden" to authenticate a rack app in the same stack as the rails app that uses devise ? My problem is that when I call this: request.env['warden'] # nil :( from the other application on the rack stack I get nil ! I integrated dav4rack (webdav) in my rails app via config.ru. I ...