I've been trying to set up a category Drafts set of permissions so that editors can work outside public view until pages are ready for public viewing, then switch the category assignment to pop the page into view for Registered and Anonymous. I haven't got it to function the way I want yet, but think I'm getting close.
Sylvie, if you are working on permissions for 1.10, it would be a really nice touch if another button were added to the editing screen called "Save." Save would save the editor's work but keep it private from all others with equal or lower permissions, including all other editors, until the "Post" button was used. As the scheme works now, people have a lot of incentive to not save their work until they have completed a page because saving displays the incomplete page. I can set this up with per-user permissions now, but an application level change seems appropriate.