I use cron to run some jobs, but since that's the only thing I use my unix mail for, having this run through Mail.app would be a nicer experience than seeing "You have new mail." in the Terminal.
How can I do this?
Brutal solution: set up postfix to handle outgoing mail, and create a ~/.forward file forwarding all mail to your "real" mail account. Not for the faint of heart but, then again, neither is running cron jobs. :)