Here's a rather silly Other Way To Do It. Look, ma, no temporary array:

my $last = (keys %hash)[-1];
foreach my $element (keys %$hash) {
   if ($element eq $last) {
       #do this
   } else {
       #do that
   }
}
[download]

I just added this as just something to play with. I don't think I'd ever use it in production code myself.