I've also implemented a privacy-ala-Moodle-Journal feature for the Wall.
A student can only view updates to the Wall posted by either himself/herself or by the Course Administrator. Posts by other students will be hidden. However, comment posts by other students can be viewed.
The screen above shows what Mr. Student, a student account, sees when he/she logs in. The content of message posts by James Dean are hidden from view. Note however that comments by James Dean are not hidden.
This feature works similar to the Moodle Journal mod. The advantage that the teacher can turn the Journal mode on by using the code &Journal=1 and then turn it off to reveal all posts and comments by using &Journal=0 in the iframe code.
For extra pizzazz, other students' avatars are grayed out. A mouseover onto a grayed-out avatar brings the avatars color back as a gradual fade-back-to-colour. I thought that was a nice touch to implement this JQuery effect.
Frankie Kam