1.4.
Automatic locking and unlocking
Up one level
When two people are working on the same content, you don't want them to overwrite each other's content — should they happen to be editing the document at exactly the same time.
Plone gives you a lightweight locking message that will tell you that a document was locked, by whom, and how long ago — so you won't accidentally stomp on somebody else's changes.
Oh, and it also gives you an easy way to unlock documents, so that document that you are looking at that says it was locked by John in Accounting 10 days ago — yes, the same guy that was telling everybody about his upcoming Jamaica vacation — can be unlocked without needing to call John or get the system administrators involved.