BuddyPress.org

I think that the easiest way to do this would be to create a form (with cforms or some other plugin) with a title section, author section, tags and categories sections, and then obviously the body section and place it on a page specifically for posting, or on the front page (which ever you prefer) then place php code around it asking if the user is logged in.

If they are, then it will show the form and they can type (or paste) their post in and it gets sent to you in email and then you can post it, if they are not logged in, it can show a “You must be logged in to post” or something to that effect.