I have a mixture of outlook clients running 2007 (SP2) and 2010 (No SP) connecting to Exchange 2007 SP3. They all utilise shared calendars and they are 90% laptop users. The problem occurs when a user creates an appointment in their calendar or their assistant creates an appointment in their calendar it does not update all views of this calendar in other people's outlook. If all users are working in online mode this is not an issue but when they are working in online mode the appointment can take up to 24hrs to update in everyone's view. This is not acceptable because none is sure of what the other is doing and therefore defeats the purpose of these shared calendars.