Wireshark will analyze wireless packets in realtime providing you have the right card/driver. I use it on my mac out of the box in the current version it will do it fabulously. Very interesting packets when looking at the 802.11n stuff. Go into interfaces, select your wireless NIC, and under the Link Layer Type, select WLAN (or 802.11 i can't remember the exact verbage of the drop down right now.)
As for PC, I am sure Wireshark does it but again it depends on the wireless NICs you have and the driver configuration. Backtrack does a pretty good job at pentesting and analysis as well in the WLAN realm but I always find myself firing up Wireshark on the mac for a poor man's analyzer.