I figured out the trust relationship between SharePoint 2010 and Exchange 2010. Now when I do a calendar overlay to a public calendar it not only displays the public calendar items but also all of calendar items in my personal calendar. I only want it to display the public calendar items for users and not their items. I am concerned that something is not configured properly as I cannot find anyone posting the same issue and I would assume that this would be a common request.
When you connect to Exchange, SharePoint will by default connect to the authenticated users calendar. I don't think there is a way to change this behavior OOTB.