Here is what I have:

 routes.php
 Route::controller('colaboradores', 'ColaboradorController');


 filters.php
 Route::filter('auth.colaboradores', function()
 {
  	 if (Auth::guest()) return Redirect::guest('/colaboradores');
 });


 ColaboradorController.php
 <?php
class ColaboradorController extends BaseController
 {
 
 public function __construct()
 {
    $this->beforeFilter('auth.colaboradores', array('except' => 'getIndex','postIndex'));
}

public function getIndex()
{
	$colaboradores = Colaborador::all();
 	return View::make('full.colaboradores.login');
} 

// pagina principal site/colaboradores autenticação de colaboradores
public function postIndex() {
	if (Auth::attempt(array('login'=>Input::get('login'), 'password'=>Input::get('password')))) {
		return Redirect::to('colaboradores/gerenciar-colaboradores');
	} 
	else 
	{
		return Redirect::to('colaboradores')->with('message', 'Your username/password combination was incorrect')->withInput();
	}		
} 

public function getGerenciarColaboradores()
    {
	   $colaboradores = Colaborador::all();
 	   return View::make('full.colaboradores.index')->with('colaboradores', $colaboradores);
    } 

So I access http://mysite.com/colaboradores and it opens the login page (working fine). Then I anything I type valid or wrong will redirect to http://mysite.com/colaboradores again, instead redirecting http://mysite.com/colaboradores/gerenciar-colaboradores if the credentials are valid.

If I remove the auth filter, everything works fine (it redirects to http://mysite.com/colaboradores/gerenciar-colaboradores if auth OK, or to http://mysite.com/colaboradores if not).

What I'm missing?