allow subscriber user roles to view private pages and posts http://cms.about.com/od/advanced/a/How-To-Let-Subscribers-View-Your-Private-Wordpress-Blog.htm

private_subscriber.php

<?php

  // Allow subscribers to see Private posts and pages
  $subRole = get_role( 'subscriber' ); 
  $subRole->add_cap( 'read_private_posts' );
  $subRole->add_cap( 'read_private_pages' );

  // Redirect to home page on login
  function loginRedirect( $redirect_to, $request_redirect_to, $user ) {
    if ( is_a( $user, 'WP_User' ) && $user->has_cap( 'edit_posts' ) === false ) {
      return get_bloginfo( 'siteurl' );
    }
    return $redirect_to; }
  
  add_filter( 'login_redirect', 'loginRedirect', 10, 3 );
  
?>