What you can’t do with the iPhone -- out of the box, anyhow -- is get the BlackBerry’s push-based approach to e-mail, in which the mail server sends messages to the device rather than requiring the device to query the server to gain access to new messages. This push-based approach makes it harder for someone to spoof the e-mail server. To push e-mail to an iPhone (or most other mobile devices), you need a mobile server such as those from Visto and Synchonica; these integrate with your Exchange or Domino server.

The iPhone also doesn’t support Microsoft’s Direct-Push approach (aka ActiveSync on Windows Mobile and Palm OS devices), which leaves the connection between the OWA (Outlook Web Access) server’s mail port and the mobile device open so that new messages are instantly visible. (The iPhone does use OWA as its connection to Exchange, just as Microsoft’s Entourage e-mail client does for the Mac OS.) Instead, you’ll have to live with the iPhone’s periodic mail checks (15 minutes is the shortest period, though you can easily find SSH hacks on the Web to reduce that window.) Rumors have been flying for months that Apple has licensed ActiveSync from Microsoft; maybe we’ll find out on Thursday whether that rumor is true.

[ See InfoWorld's in-depth reviews of the iPhone and iPod Touch ]

Accessing calendars and other shared data
The biggest issue Exchange and Notes shops will face in business-enabling the iPhone is providing access to calendars, address books, and other PIM data beyond e-mail.

Calendars and contacts can be synchronized between Exchange and the iPhone, but this must be done through iTunes, meaning you will need a PC or Mac to act as an intermediary.

For Windows (XP or Vista) shops tapping Outlook 2003 or 2007, syncing is straightforward through iTunes. Connect the iPhone to your intermediary PC and select it in iTunes’ Devices list. Open the iTunes device Info pane and choose the calendars and contact sources you want to sync. If you have problems, consult Apple’s common fixes.

On the Mac, use the built-in iCal and Address Book software as the way station, and then configure Entourage to sync with them (use the Sync Services pane of the Preferences dialog box). In iCal, you must create and use a calendar called Entourage for any entries you want synced to Exchange. (And Exchange calendar items will be placed in iCal in the Entourage calendar as well.) Then, with your iPhone physically connected and selected in iTunes’ Devices list, open the Info pane to choose the calendars and contact sources to be synced. All three programs -- Entourage, iCal, and iTunes -- must be set up properly for this ménage à trois to work.

A tip: In Entourage’s preferences, choose whether to sync your server’s calendar or your local calendar. If you change this setting, it’s very likely that your calendar will stop syncing. It turns out the issue is in iCal: You’ll see multiple Entourage calendars listed (one for each time you changed the setting in Entourage). Delete all but the “real” Entourage calendar (you can right-click on a calendar and choose Delete from the contextual menu).

Likewise, for Notes on the Mac, iTunes is the go-between, as described for Exchange -- and you will need a separate app such as Information Appliance Associates’ PocketMac GoBetween to make iCal and Address Book sync with Notes. Ironically, there doesn’t appear to be a way to get calendar and address book data from Notes to the iPhone in Windows. If IBM follows up on its promise to ship a Notes client for iPhone, there’ll be no need for a third-party app or other work-around.