Wifi interface doesn't appear as an interface you can add a scheduler (ie PRIQ) on
Traffic Shaper (ALTQ)
Plus Target Version:
I have 2 urtw wireless NICs on my pfSense that don't even appear on the list of interfaces in the traffic shaper where you can create a queue.
Circumstance and background here: http://forum.pfsense.org/index.php/topic,26782.0.html