I am sorry for my ignorance, but I noticed a lot (if not all) WiFi chipsets are sporting an ARM or other CPU (even the one in PC's!). Now I recall most Ethernet chipsets did not need a CPU (although it was advantageous).
Why is it that wifi chipsets need a CPU? Is it because of the encryption (WEP, WPA)? Or is there something else in the physical layer that cannot be handled economically in hardware?