Let's get rid of the $state variable. 
#!/usr/bin/perl -l -w0777

@users{split /\s+/, <DATA>}=();

while(sleep 2) {
  $_ = `users`;
  for my $n (keys %users) {
    if ($users{$n} xor /\b$n\b/) {
      $users{$n} = /\b$n\b/;
      print localtime() . " $n has logged ", $users{$n} ? "in" : "out"
+;
    }
  }
}

[download]
UPDATE: There are a number of golf tricks that I've left out. For instance ("out", "in")[$users{$n} = /\b$n\b/] manages to both remember and select the current state, removing one line. But readability suffers.

In reply to Re^2: Shorten this code by tilly
in thread Shorten this code by hostyle

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