I stumbled upon a great Greasemonkey script for clearing your Facebook wall of all posts, of any type. It seems to work very well, so I recommend it to anyone looking to do some cleaning up without having to press the same buttons over and over a thousand times.

Install Greasemonkey for Firefox, restart the browser, then install the Clear ALL Facebook Activity (fixed) script.

A button should appear on your profile page when installed (refresh may be needed).

I updated the original creator’s script to work in the new Facebook profiles.

EDIT 2012.18.01: The script needs to be revised for the new Facebook “Timeline” profiles.
However, should you still find use for it, please let me know if it still works or not.