@List = ();

$List[0]->{'time'} = "00:34:20";
$List[0]->{'date'} = "2011-09-13 00:34:20";
$List[0]->{'file'} = "abc.txt";
$List[0]->{'note'} = "dummy1";

$List[1]->{'time'} = "00:37:12";
$List[1]->{'date'} = "2011-09-13 00:37:12";
$List[1]->{'file'} = "abc1.txt";
$List[1]->{'note'} = "dummy2";

$List[2]->{'time'} = "00:33:00";
$List[2]->{'date'} = "2011-09-13 00:33:00";
$List[2]->{'file'} = "abc2.txt";
$List[2]->{'note'} = "dummy3";

my @sorted = sort { $a->{'date'} <=> $b->{'date'} } @List;