title: Rails 3 Join question
body: <p>Hey there,
    i have a user model, a discovered_locations model and a boss_locations model.</p>
  
  <p>A boss_location is the static representation of a boss location. A discovered location is (user_id, boss_location_id).</p>
  
  <p>What is a nice way(even better if a scope is involved i guess), to get a join of the user boss locations and discovered locations ?</p>
  
  <p>That is, i want to get a join on the boss locations. I want all the boss locations, either discovered or not, but i want to also know if they are discovered.</p>
  
  <p>How would you do that ?</p>