Here you go:

    for my $auth (sort { $hash{$b}{count} <=> $hash{$a}{count} } keys 
+%hash) {
        print FILE "$hash{$auth}{fname} $hash{$auth}{lname}: $hash{$au
+th}{count}\n";
    }
[download]

This will sort by count in reverse numerical order, from biggest count to smallest. If you want it the other way round, swap the $a and $b.