title: What is the _snowman param in Ruby on Rails 3 forms for?
body: <p>In Ruby on Rails 3 (currently using Beta 4), I see that when using the <code>form_tag</code> or <code>form_for</code> helpers there is a hidden field named <code>_snowman</code> with the value of ☃ (<a href="http://en.wikipedia.org/wiki/Unicode" rel="noreferrer">Unicode</a> \x9731) showing up.</p>
  
  <p>So, what is this for?</p>