Vertical Menu in Bootstrap

The question is old now.

But if somebody looks here the trick in the current version is to use the nav-stack class, like so:

<nav>
  <ul class="nav nav-pills nav-stacked span2">
    <li><a href="#">Home</a></li>
    <li><a href="#">About</a></li>
    <li><a href="#">Contact</a></li>
  </ul>
</nav>