Count me as among the disappointed. My company does not have IMAP enabled for the Exchange server, so I understand (now) that Mail.app won't work.
What is beyond frustrating is that Entourage works fine just be entering my OWA address, company user name, and password. No VPN needed.
Heck, my lowly Sprint LG Rumor 2 mobile phone can sync with my work emails, contacts, and calendar via it's email client and yet Mail.app cannot because it can't connect through OWA without using IMAP? Is there a reason this functionality is not present in Mail.app and that I am still going to have to use Entourage for my work email? If a stupid dumphone (is that redundant?) can do it, I see no reason why mail.app cannot.
And in my mind, this is an issue with Apple...not an issue with my company's nearly non-existent IT dept or with MS.
Bottom line, Entourage can do it and my stupid phone can do it. Mail.app cannot.