I was curious enough to try it...

# perl -MData::Dump=dump -e '$h = {lol=>2}; $h->{lol2} = $h; print dum
+p($h), "\n"'
do {
  my $a = { lol => 2, lol2 => 'fix' };
  $a->{lol2} = $a;
  $a;
}
[download]

That really is pretty slick looking compared to Data::Dumper. I'm not going to switch or anything, but you can't deny the output looks cooler. Less efficient maybe, but cooler...