I think you should add this _cool_ feature to the sample pf.conf in /etc ... it's "hidden" in /usr/share/pf/ in the current snapshot and in order to announce it some more you should maybe put an exsample in the /etc/pf.conf file for everybody to see. btw, a link to your tutorial and motivation (http://www.benzedrine.cx/ackpri.html) in /usr/share/pf/ackpri couldn't hurt.
that's all for the moment
Max
