Hi nelio.

You really should follow Limbic~Region's tip, by using POSIX' strftime, which is bundled with Perl or DateTime.

I would also to add another alternative (which you should not use in production environment):

sub format_date {
    return join ".", (reverse unpack "A4xA2xA2", shift);
}
[download]

Update: I think it is ok use this if you know what are you doing and you will not perform any date calculation with it.