title: Rails3.0.0Beta4 setting session store to database
body: <p>I am porting a Rails 2.3.8 app to Rails 3.0.0Beta4.  I can't get the session to be written to the database instead of cookies.</p>
  
  <p>I do the following in <code>config/environments/development.rb</code>:</p>
  
  <pre><code>config.session_store(:active_record_store)
  </code></pre>
  
  <p>The session store is set correctly - I verify that by dumping <code>config</code> after the set.</p>
  
  <p>What am I missing?</p>