Well, sure, that's more-or-less exactly what memcached is doing. You could write memcached in Perl and call it foo.pl if you wanted. I think you might be focusing too much on Perl's namespace. Perl namespaces are just hashes, just the same as the hash that memcached supports, so all the same techniques apply.

If you want to learn more about networking with Perl, I suggest you pick up a copy of Network Programming with Perl. I'm sure it has examples of the kind of thing you're talking about.

-sam