This ActiveForums page (http://www.activemodules.com/ActiveForums.aspx) claims that AF has private messaging capabilities:
"You and your users will enjoy using the AJAX control panel, points and rewards system, advanced profile and private messaging options, and many more beneficial features."

I don't see PM capabilities in my Active Forums 4.3.3.0 Express Edition... am I just missing it or do I need to upgrade to a later version/higher level?

Thanks,
Jeff

Active Forums does not actually have private messaging, it just supports other private messaging module integration. (Active Social and Ventrian private messaging)