Calendar Sharing in OWA
How to open another users's calendar when using Outlook Web Access
The 2007 version of OWA (Outlook Web Access) includes an easy way to open the mailbox of another user, but no similar feature exists for opening specific folders of other users. To open another user's calendar in OWA you need to enter a very specific URL in the address bar of your browser.
Here is an example URL for a user's calendar. Replace the 'user@domain.com' portion of the URL with your colleague’s email address. Change monthly to weekly or remove the last portion of the URL for the default daily view.
Here is an example URL to open another user's calendar:
https://shelley5.webville.net/owa/user@domain.com/?cmd=contents&f=calendar&view=monthly
Consider creating the different ones you need and adding them as favorites in your browser favorites, or making icons on the desktop for the URLs. You sure don’t want to type them manually!
The system will prompt you to log in if necessary. If your colleague has the appropriate permissions, which you would have granted them in Outlook, OWA will display your calendar for them.
See Open Other Users Folders for how to grant the necessary permissions so others can open your calendar this way.
Reference:
http://msexchangeteam.com/archive/2006/11/28/431665.aspx