Worksharing Monitor tells you who else is working in your shared central file. It tells you when they are saving to central, and when your local file is out of date (due to someone else saving to central). It also handles editing requests, and lets someone else know if you want to edit an element they currently have checked out.
Want to chat with them but someone put super glue on your chair so you can't get up? Use Cisco Personal Communicator to open a chat box with them and ask them to relinquish an element, or to tell them to change it back because you just fixed it! (you will need to add everyone individually in Personal Communicator)