usando la favolosa Serializer di sephiroth ...

file prova.php
codice:
<?php
$ar = Array();
$ar[0] = 'pluto';
$ar['pippo'] = 'paperino';
echo '&array='.urlencode( serialize( $ar ) );
?>

in flash
codice:
var fromPHP:LoadVars = new LoadVars();
fromPHP.onLoad = function( s:Boolean ):Void {
	if( s == true ) {
		import it.sephiroth.Serializer
		var unserialized:Object = new Serializer().unserialize( this['array'] );
		
		// PROVA
		trace( unserialized.pippo ); // paperino
		trace( unserialized[0] ); // pluto
	}
}
fromPHP.load( 'http://localhost/prova.php' );