This customer also has an issue with the calendar. I did a test and get the same results.
I then did a test on our AppRiver Hosted Exchange 2010 account and the calendar shows up fine on the mac, just like the pc. So, yes, it does work on Exchange 2010.
So, I have narrowed down the issue to be on the Microsoft side.
I am going to open up a Service Request with Microsoft now and then call them because i get someone on the phone as soon as i call.
I will update this thread later.