As of wagn 1.13.0 this is no longer needed, but might still be relevant to some users:
You will need to pay special attention to the public directory. Because Wagn is still transitioning its javascript into cards, it is still using the public directory from the Wagn gem and not from the individual Wagn installation. The temporary fix for this is to create a symbolic link to the gem's public directory.
So if you created a new wagn in /srv/mywagn, let's call that's your "appdir". And if your wagn gem is stored in /usr/local/rvm/gems/ruby-1.9.3-p374/gems/wagn-1.12.12, that would be your "gemdir". You can find out where your wagn gem is located using `bundle show wagn`. The public directory link you need is something like this:
> cd [appdir]; ln -s [gemdir]/public