How to get Twitter-Bootstrap navigation to show active link?

You can use something like (very similar to what @phil mentioned, but a little shorter):

<ul class="nav">
  <li class="<%= 'active' if current_page?(root_path) %>"><%= link_to "Home", root_path %></li>
  <li class="<%= 'active' if current_page?(about_path) %>"><%= link_to "About", about_path %></li>
  <li class="<%= 'active' if current_page?(contact_path) %>"><%= link_to "Contact", contact_path %></li>
</ul>

Just made an answer on the very same question here Twitter Bootstrap Pills with Rails 3.2.2

<ul class="nav">
  <li class="<%= 'active' if params[:controller] == 'controller1' %>"> <a href="/link">Link</a> </li>
  <li class="<%= 'active' if params[:controller] == 'controller2' %>"> <a href="/link">Link</a> </li>
  <li class="<%= 'active' if params[:controller] == 'controller3' %>"> <a href="/link">Link</a> </li>        
</ul>

https://github.com/twg/active_link_to

<%= active_link_to 'Users', users_path, :wrap_tag => :li %>

#=> <li class="active"><a href="/users">Users</a></li>