I've been looking all over trying to find cron for the iPhone and it looks like this thread is trying to do the same. Then I read about the launch daemon. It implements everything that cron can do. In fact, in Leopard (from what I read) cron was excluded in the os. And it looks like it's this way in the iPhone OS now. There's a page out there that shows how to take cron tasks and change them so they work with the launch daemon.