Well, I've already golfed it down to 30 chars, but I thought you might enjoy this rather bizarre one at 33:

sub u {
  delete@h{grep$h{$_}++,@_};keys%h
}
[download]

As with yours, my%h; should really be prepended to make the sub reusable.

   MeowChow                                   
               s aamecha.s a..a\u$&owag.print