The following two array looping statements are not equal
(Assuming Update() updates some instance variables in the 
object)

foreach( $objs as $o )
   $o->Update()


and


for($i=0; $i<count($objs); ++$i)
   $objs[$i]->Update();


In the first case the Update() method will change an anonymous copy of the object in the array while in the second case the update will work on the object in the array. Hence any changes that Update() might do will in the
first case not be done for the objects in the array.

Not sure if this is a genuine bug or just a consequence of the copying semantics for objects in PHP.