Mac/iPhone: Connect the iPhone to Microsoft Online Services
The new iPhone 3G that came out last week final enabled Exchange ActiveSync support. As a result, you can now connect your iPhone 3G or the older iPhone with the new 2.0 firmware to connect to Microsoft Online Services.
Simply goto Settings->Mail, Contacts, Calendars->Add Account->Microsoft Exchange.
Email: enter your email address
Username: enter your email address
Enter your password and description for the mailbox.
Click Next
Accept the verify certificate pop ups.
You will now see a new screen with an extra blank entry for Server. Enter the OWA address. In beta, this is "red001.mail.microsoftonline.com".
Select the information you want to synchronize, and click on Save.
Note: The above information is provided as-is and is BEST EFFORT supported by the Microsoft Online Support Team