E-Mail Setup/iPhone Mail
iPhone allows you to synchronize your mail accounts via iTunes. To do this, set up your OS/X Mail application, so you can view your mail in that desktop application, then select your IVS account for synchronization to your iPhone in iTunes under the iPhone's "Info" tab in the "Mail Accounts" section.
At this time (iPhone software revision 1.0), there is one additional step that you'll need to complete. From the main menu page, select Settings | Mail | <Account Name> | Advanced | IMAP Path Prefix, then enter "INBOX" (in all caps). Now you'll be able to see all IMAP folders that you use in webmail or in your IMAP client. You can also set your Drafts, Sent, and Deleted Mailboxes to folders that reside on the server, so you can see items sent from your iPhone in your desktop application, and vice versa.