Thanks, I will look at that.
I also found an app called "Lookee-Loo" for this purpose, but the interface is apparently not great. And it requires Exchange 2007; my mother's office is still on Exchange 2003.
There also was an app called iExchange Calendar at one time but it was removed.
I have to say I am surprised that it is so difficult to figure this out...seems like a large user base has shared calendars in Exchange.

