Hi. We use Portal.microsoftonline.com with Windows and MAC clients.
One Windows client shared him Calendar, but with rights "Folder Visible" or "Free\Busy time".
Another Windows client added this Calendar and can see only "busy" meeting.
In same time MAC client added this Calendar and can't see anything.
Then owner Calednar change permissions to "Free\Busy time, subject, location".
Now Windows client can see Free\Busy time, subject, location, but MAC client still can't anything.
And, when on MAC i look Shared Permission - they not changed. Still "Folder Visible".
Why MAC client can't see anything??? Why shared Permission not changed???

I have test Exchange 2010 SP3. I have configured there same infrastructure, and With Exchange 2010 SP3 MAC client can see shared Calendar!