WordPress simple bootstrap-menu like this: http://twitter.github.com/bootstrap/components.html#navbar

menu.php

<?php wp_nav_menu( array( 
  'theme_location'      => 'primary', 
  'container'           => false,
  'items_wrap'          => '<ul class="nav">%3$s</ul>',
  'walker'              => new Bootstrap() 
) ); 
?>

Walker.php

<?php 

/**
 * Class Name: Bootstrap
 * Author: Pontus Abrahamsson
 */
 
class Bootstrap extends Walker_Nav_Menu 
{
    function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) 
    {
        $sel = null;

        if( is_array( $item->classes ) && in_array( 'current-page-ancestor', $item->classes ) || $item->current )
        {
            $sel = 'active';
        }

        
        $output .= '<li '. ( isset( $sel ) ? 'class="'. $sel .'"' : null ) .'>';

        $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->title .' '. $item->attr_title ) .'"' : null;
        $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target ) .'"' : null;
        $attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn ) .'"' : null;
        $attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url ) .'"' : null;

        $item_output = '<a'. $attributes .'>';
            $item_output .= apply_filters( 'the_title', $item->title, $item->ID );
        $item_output .= '</a>';


        $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
    }
}