This is another approach that might not be shorter, but does work with ruler lengths that aren't a multiple of 10. Update: Just noticed that petral does it more neatly.

#!perl -w
use strict;

print ruler(@ARGV);
sub ruler {
  my ($x,$y) = (' ', '');
  map{$x.=sprintf('%10d',$_/10) if $_%10 == 0 && $_ != 0; $y.=$_%10} (
+0..$_[0]);
  return "$x\n$y\n";
}
[download]

I would have liked to use for rather than map, but I couldn't get the 1 line version to compile ;-(

I also can't get it to work with non-positive integer values ;-((.