Microsoft Exchange Server gives you the ability to share your calendar and open other users calendars, providing you have been given appropriate access.
In order to share your calendar with another person select Share:
Figure 1: Share command, select Share This Calendar
Calendar Sharing Invitation.
Select who you would like to share your Calendar with by clicking To and choosing them from the Global Address list, next choose what options you would prefer. When your invitation is completed hit the Send button
Figure 2: Calendar sharing invitation
Calendar sharing invitations will look like this:
Figure 3: Calendar invite
In order to open a Calendar from the Sharing Invite click on Add This Calendar:
Figure 4: Add this calendar command
You will now see the additional Calendar in the navigation pane within the Calendars in OWA. To view the Calendar you have been given access to simply click the check box next to the Calendars name.
Figure 5: Calendar Navigation Pane
Notice when viewing more than on Calendar at a time the Calendars are displayed in side by side mode:
Figure 6: Two calendars opened in side by side mode