If I'm using multiple languages on the site with path prefixing, is there a quick way to get a system path for the current language?
For example, if the current language is English, and I'm interested getting the English path for 'user/password', what function call (or small number of lines) will return 'en/user/password'?
The following doesn't seem to work; it returns nothing:
drupal_lookup_path('alias', 'user/password', $language->language); The internal path is same for all languages,though you can set different alias for different languages. From your question it seems that you want to get the path with language prefix not the alias, if so then I don't think there is any function that will return the path with language prefix.
Since you can get the language using $language->language you can write a custom function as follows.
function custom_lookup_path($action, $path = '', $path_language = NULL){ global $language; if(empty($path_language)){ $path_language=$language->language; } if(!empty($language->prefix)){ $path = $language->prefix.'/'.drupal_lookup_path($action, $path , $path_language); } else{ $path = drupal_lookup_path($action, $path , $path_language); } return $path } 
$language->language?