I'm baffled as to how many posts and threads there are on this topic- I don't have time to read all of them. But really, locking a notebook cannot be that hard to implement. I use EN to store all kinds of content quickly from many devices- like 20+ notes per day. I don't have time to sort through all the notes and tag them and put them in their own notebooks. I have assistants who do this. I don't want these assistants looking at some of the notes. To have one notebook where I can stash private notes would be ideal. I can't think of a successful database-driven service that does not offer this. Maybe Evernote is just waiting to cash out from a buyout- maybe Google can come to the rescue.