Feature suggest: Private by Default

I’ve been trying to find a plugin that will make new posts private by default. This feature is very important if you’re using WordPress as a CMS. Example case is building a website for a community, user posts usually should not visible to public.

Information about private post:
http://en.support.wordpress.com/posts/post-visibility/

Actually I have found one, but it seems the author has abandoned it, he has no any activity since 2 years ago. Here is the plugin:
http://ww.wp.xz.cn/plugins/private-post-by-default/

It would be great, if you can fork the plugin and add some new features, like private by default per category and/or custom post type.

http://ww.wp.xz.cn/plugins/many-tips-together/