Ruby really is Perl done right. I can't really see any argument for Perl over Ruby as a language.
use strict. In Perl you can prevent something like the following from compiling. You can't with Ruby (unless they've finally addressed that).
$foo = 2;
if (some_test()) {
$fooo = 3;
}
Shouldn't that be:
my $foo = 2;
?
I was leaving the declaration implicit.
Speed. I moved mostly to Ruby years ago, but when doing lots of text processing, a trivial script in Perl runs a lot faster than a similar trivial script in Ruby.
You should see some of the atrocities I had to debug at aol because of regex abuse.