I am sharing this as couple of my customers were enquiring is there any changes or effects of Client Shutdown in MAPI (Outlook 2010 fast shutdown). 

MAPI clients can shut down the same way as before, or if needed, they can use fast shutdown. In Outlook 2010, MAPI subsystem provides the IMAPIClientShutdown : IUnknown interface. If a MAPI client needs to adopt fast shutdown, then they can make use of it. In order to implement the shutdown, MAPI client to initiate a quick shutdown of the client process, notifying all providers with which the client has an active MAPI session to save data and settings before the client process exits.

For more info, you can refer the related articles:

Fast Shutdown Overview: Basic mechanism of fast shutdown
Fast Shutdown User Options: Choices available for administrators to adopt fast shutdown at the user level for the user’s MAPI Clients
Best Practices for Fast Shutdown: best practices to use the fast shutdown interfaces to help prevent data loss during a MAPI client shutdown.

You can refer Ryan’s post, along with couple of related articles by Steve @ Fastest Shutdown In The West and When I Say Shutdown, I Mean Shut. Down.

Happy programming!!