just a couple'a navs, hangin out. http://jsfiddle.net/rz85X/18/

multi-nav.html

<div class="navbar">
  <div class="navbar-inner">
    <a class="btn btn-navbar" data-toggle="collapse" data-target=".col2">groups2</a>
    <a class="btn btn-navbar" data-toggle="collapse" data-target=".col1">groups</a>
    <div class="nav-collapse col1">
      <ul class="nav">
        <li><a href="#">Nav Link</a></li>
        <li><a href="#">Nav Link</a></li>
        <li><a href="#">Nav Link</a></li>
        <li><a href="#">Nav Link</a></li>
      </ul>
    </div>
    <div class="nav-collapse col2">
      <ul class="nav">
        <li><a href="#">Nav Link2</a></li>
        <li><a href="#">Nav Link2</a></li>
        <li><a href="#">Nav Link2</a></li>
        <li><a href="#">Nav Link2</a></li>
      </ul>
    </div>
  </div><!-- /navbar-inner -->
</div>