An interesting post was posted at Communications Server Team about Enhanced Presence in OCS 2007.
What is Enhanced Presence?
OCS 2007 allows its client applications to publish and subscribe to Enhanced Presence information. The enhanced presence infrastructure includes categories and containers. State, note, contact information, or calendar data (e.g. Free/Busy) are examples of categories. Containers are logical buckets into which the clients publish the categories of presence information.
A user can control what presence information other users see. For example, if [email protected] places [email protected] in his Public container, userB can see only userA's name, e-mail address, and basic contact information. If userA places userB in his Personal container, userB can see detailed information like additional phone numbers, location etc.
Read more at source: http://communicationsserverteam.com/archive/2008/05/21/184.aspx