Here we have another OBEO related enhancement request that was once approved for a future release, but that was dropped later on:
OBEO currently does not show who was the latest user that modified an artifact like a contact or a calendar entry.
In a collaboration environment this would be an essential information to have.
So please do second the following enhancement request through MOS:
ER 10414128: MAKE CREATOR/MODIFIER VISIBLE FOR CONTACTS, CALENDER ENTRIES