title: sinatra app doesn't start on run
body: <p>I'm on Ubuntu 10.10/Ruby 1.9.2</p>
  
  <p>Whatever I do, I can't get a sinatra app to start on my local machine. </p>
  
  <p><strong>hello.rb:</strong></p>
  
  <pre><code>require 'sinatra'
  get '/' do
    "Hello World!"
  end
  </code></pre>
  
  <p>"$ ruby hello.rb" and "$ ruby -rubygems hello.rb" both result in a new prompt with no action taken.</p>
  
  <p>Any tips or pointers? </p>