Activity API - more bugs

Just noticed that civicrm_activity_create no longer accepts custom fields. The format $params['custom_9'] = 'some string'; used to work. Now it doesn't.
One note while we're working on this: It would be great if it would support multi-value fields. Currently (at least until it recently stopped working) it only supports single-value fields. I would suggest multi-value fields should get their data passed as an array like so:
$params['custom_9'] = array('some string', 'some_other_string');

One more bug to report: Some work has been done on the validation troubles of this API, but it continues to act up for me (so I continue to manually disable the validation in activity.php so as not to break my modules). Trying to add an activity that is part of a case still will not pass validation, even though the actual function works fine.