I often hear from users that they don’t like to use Outlook Web App  for email because they can’t see shared calendars.  I then inform the user that things have changed since the days of Exchange 2003. A nice added feature of Outlook Web App 2010( Outlook Web Access) is that you can use the Change Sharing Permissions within Outlook Web App to view the people you’ve shared your calendar with and the permissions they have. This also gives you the ability to stop sharing your calendar. Now you can’t use Outlook Web App  to give someone else permission to change your calendar, but you can use the Delegate Access feature in Outlook to give other people in your organization permission to make changes to your calendar and to respond to meeting requests on your behalf.

To Modify Calendar Sharing Permissions :

1. In Outlook Web App, click Calendar in the Navigation Pane.
2. Click Share on the Calendar toolbar.
3. Click Change Sharing Permissions and then, in the Calendar dialog box, select the name of the calendar that you want to change sharing permissions for.
4. Click the name of the person whose permissions you want to change.
5. Click Edit and select the permissions you want.
6. Click Save to save your change.

How to stop sharing a calendar:

If you want to stop sharing your calendar with someone:

1. In Outlook Web App, click Calendar in the Navigation Pane.
2. Click Share on the Calendar toolbar.
3. Click Change Sharing Permissions and then, in the Calendar dialog box, select the name of the calendar that you want to stop sharing.
4. Click the name of the person you want to stop sharing your calendar with to select it, and then click .
5. Click Yes to confirm that you want to delete that person from the list, or click No to cancel.

So there you have it. Next time a user says they don’t like to use OWA because they can’t manage or see shared calendars you can let them know that’s not the case anymore.