How to find out what views page you're looking at
Use menu_get_item() to retrieve the page callback for the currently shown path, and check it correponds to 'views_page', which means you are in a view.

function mycooltheme_preprocess_page(&amp;$vars) {
  $menu_item = menu_get_item($_GET['q']);

  if ($menu_item['page_callback'] == 'views_page') {
    $vars['is_portfolio'] = ($menu_item['page_arguments'][0] == 'path_of_your_view');
  }
}


You can also use current_path() directly, but I found interesting to know that you're on a Views page using menu_get_item().