Versions is nice. After you first save the file every subsequent manual save creates a version. There are consequently not only the automatic hourly versions.

Versions is nice. After you first save the file every subsequent manual save creates a version. There are consequently not only the automatic hourly versions. The UI is a bit clunky, though. OS X switches to a fullscreen Time Machine view which felt way too jarring to me. The locking behavior is also very well thought out. Additionally to automatically locking documents after two weeks, Lion also (better) exposes this functionality in the UI. All this helps to make it much less likely that you will ever accidentally overwrite an old document you used as a template. (When you start editing a locked document a dialog pops up telling you that the document is locked and the default option is not unlock but duplicate which is great.)