If you've had trouble logging into the Lion Server App (not Server Admin, the other one) after setting up your server... it's probably not your fault.  While troubleshooting the issue on a client's brand new Mac Mini Server, one of our consultants -- Tito Lauro -- found a knowledge base article with a great fix.  Initially, it may appear that your credentials are incorrect but it's most likely related to an unloaded background process (daemon) called [...]