How to correctly handle date formats that needs i18n
Try something like:

$text = t("Some text @date more text @time", array(
  '@date' =&gt; format_date($timestamp, NULL, 'Y-m-d'),
  '@time' =&gt; format_date($timestamp, NULL, 'H:i'),
));


More info at:


http://api.drupal.org/api/drupal/includes%21bootstrap.inc/function/t/7
http://api.drupal.org/api/drupal/includes%21bootstrap.inc/function/format_string/7