It might be the case that simply saving the document creates a new version. Not exactly version control but quite good compared to nothing. Apple tends to omit details like that.
The guidelines say that apps should auto-save their documents on Lion, and you can bet Apple'sown productivity suite will. So snapshotting every 2 seconds might not work out too well.
I was obviously referring to saving manually. If that’s no longer possible they could just replace the the save command in the menu with a “Create Version” command and Command+S could create a version instead of saving.