I'm using Lion's iCal and Mail.app, and I've started working in a company where everyone uses MS Exchange. I haven't connected iCal to Exchange. When I receive an event invitation (sent with Outlook) by email in Mail.app, I get the normal options of Maybe/Decline/Accept. When I click Accept, the sender is notified and the email is moved to the Trash. But the event itself does not show up in iCal.
I've poked around a little already. The entire invitation email is base64 encoded and has a vCal attachment with the event. When I manually base64-decode the attachment and put it into a file, I can double-click it, and it gets imported into iCal.
But I guess this is supposed to work automatically when I click Accept. Of course, in Mail.app's prefs, the "Add invitations to iCal" setting is set to "Automatically".
Is there a way to make this work properly?