$str='1234<IMG SRC="74.swf"/>56的78<IMG SRC="68.swf"/>';
$arr1=preg_split('/<.*>/U',$str);
array_pop($arr1);
preg_match_all('/<.*>/U',$str,$arr2);
$arr3=array_merge($arr1,$arr2);
print_r($arr3);Array
(
    [0] => 1234
    [1] => 56的78
    [2] => Array
        (
            [0] => <IMG SRC="74.swf"/>
            [1] => <IMG SRC="68.swf"/>
        ))