When I try:

#!/usr/bin/perl -w
use strict;

sub System {
  print "System\n";
}

sub out {
  print "out\n";
}

System.out.print("Just another perl hacker?");
[download]

Update:

#!/usr/bin/perl

# comment out these two lines to change meaning of construct in main
sub System { return "SystemSub " }
sub out { return "OutSub " };

my $val = main();
print "\n'$val'\n";

sub main {
  System.out.print("Just another perl hacker?");
}
[download]

-Blake

Yes, this is called the "poetry optimization" since its reason for existing was partly to make it easier to write poetry in Perl.