The 2nd argument to [man]date/man in PHP should be a Unix Timestamp.
I don't know off the top of my head if [man]strtotime[/man] can convert that ... you might try:
echo date("d M yy",strtotime("2011-10-18 09:25:05"));
And see if that gets you want you want. Otherwise, there are various other date functions and strategies, one of which might be to ask the database to give you a Unix Timestamp instead of the DateTime it has by default, maybe like this:
$sql = "select from_unixtime(my_date_field) as timestamp from my_table;";
//do the query & etc.
echo date("d M yy",$timestamp_var);