title: Listing the latest unstable gem version?
body: <p>When I do:</p>
  
  <pre><code>gem search -r rails
  </code></pre>
  
  <p>It shows me:</p>
  
  <pre><code>rails (2.3.8)
  </code></pre>
  
  <p>But how do I know the latest unstable version which is 3.0.0.rc so that I can use it:</p>
  
  <pre><code>gem install rails --version=3.0.0.rc
  </code></pre>