====== array_multisort ======
<code php>

// $items is a keyed/associative array; each item has various key value
// combinations as well, one of which is a date timestamp

reset($items);
foreach($items as $key=>&$item){
	$sort[$key] = $item['datestamp'];
}

array_multisort($sort, SORT_DESC, $items);

// $items is now sorted by date

</code>

The trick is knowing the key for the value you are sorting with, and putting the parameters in the correct order to array_multisort.  If you don't have a keyed array, you just need to figure out the index number (0, 1, 2, etc...), since all arrays are really keyed in some fashion anyway.