Break out the bulky, slow Date::Manip.

...
use Date::Manip;

  if (/>Updated: (.*?)</ && $date = ParseDate($1)) {
    &do_something_with($date);
  } else {
    warn "no parsum date!\n";
    &fail_gracefully;
  }
[download]

Date::Manip does have the advantage of parsing almost anything that can be a date.