http://codepad.org/mDvRJ534
<?php
$array1 = array(1299147500,1299147453,1299146476,1299143220,1297934349,1297845742,1297695551,1296134251,1295948452,1295554308,1295369389,1295345559,1295261432,1295014784,1294929846,1294832875);
$array2 = array();
$date1 = strtotime('Thursday February 17, 2011');
$date2 = strtotime('Thursday March 3, 2011');
foreach($array1 as $timestamp){
if($timestamp <= $date2 && $timestamp >= $date1)
$array2[] = $timestamp;
}
echo 'date1 = '.$date1."\n";
echo 'date2 = '.$date2."\n";
print_r($array2);