Receive email on iPhone Exchange 2003 environment

Has anyone gotten an Iphone to get email directly from an Exchange 2003 server? While my setup works with BlackBerries, I had a user go against the grain and buy an iPhone of his own and he expects to use it in my environment.

I’m trying to help the guy out, but I do not want to spend more time than necessary. So before I even start trying solutions: Has anyone else gotten it to work?

I don’t want to push through outlook, or forward to gmail or anything else.

Part of the reason I don’t want to get too involved is that he can simply navigate to my OWA site for his email which would take maybe 5 seconds longer to enter his credentials.

I do have Imap4 and OWA running currently.