BEGIN {
   my ($add_ts) = @ARGV;
   eval 'use subs qw( die )' if $add_ts;
}

sub die {
   my $ts = '[' . localtime() . '] ';
   my $msg = join '', @_;
   $msg =~ s/^/$ts/mg;
   CORE::die($msg);
}

die("foo\n");

##</code><code>##

>perl test.pl 1
[Sun Aug 23 11:52:55 2009] foo

>perl test.pl 0
foo