I heard that WiFi signals are not encrypted and can be read. Is there possibility to encrypt signal with software or hardware? I mean if WiFi card could encrypt outgoing signal and decrypt incoming signal it would work? Does that mean router also must do same thing to talk and understand WiFi card?
UPDATE: People what does WPA/WEP has to do with my question? I am not talking about protecting access points, i am talking about protecting data which travels through Wi-Fi signal against packet sniffing.

Each wireless network device encrypts the network traffic using a 256 bit key.– AndrejaKo Apr 10 '11 at 11:48