Morten, yes, that step is the Full Joomla User option, which lets the user set the username and password for their account. If you disable the email field from showing on the registration form, it's just those 3 fields (username, pass, and verify pass). There is no really, really short form that's just a username though.
Hope that answers your question and helps you get everything setup just how you want!
Username and Facebook login
