class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
more info about the class
$u = new upload($_FILES['Filedata']['tmp_name])
$u = new upload($_FILES['Filedata'])
$u->no_script = false;
should be:
(beware of multiple uploads, check the FAQ if you upload several files at a time)
Also try to set no_script to false:
Do you use the 0.26RC1?