Tesfaye:

I believe you can find the date the appointment was last modified and the
date the appointment was created, but not who updated it.

What we do at our site is require everyone who updates a shared calendar to
put their name or initials down in the comments field of the appointment.  
Then, if something arises, we know who to contact.

To find the create/last mod date, change the calendar view to one of the
table views, such as Active Appointments.

1.  Change to the calendar you're interested in.
2.  Go to View, Arrange By, Current View, Active Appointments.
3.  Right-click on any column header and select Field Chooser
4.  For the create date, scroll down the list until you find an entry called
Created.  
5.  Left-click on the Created bar and drag it over to the column headers.  
The icon should change to a red upward-pointing and a red downward pointing
arrow when you get to a place you can drop it.
6.  Let go of the Created bar to drop it in that location.  You can then
click on the bar to sort by the Create date.

The steps are similar to find the last modification date, except that when
you get to the Field Chooser, you have to use the drop down at the top of the
Field Chooser window to change your selection options to All Appointment
Fields.  Then the option for Modified will appear in the list and can be
dragged over to the calendar view.

Good luck!

tbgg
TrueBlueGeekGirl