What WiFi adapter can I use to monitor a WiFi network on OS X from a MBP? I have MBP from early 2011 and Wireshark 1.8rc2 does not recognize it (under Lion).

What adaptors are compatible with it?

Alternatively, specify if there is a another software that I can use to monitor the traffic on a specific WiFi network (not encrypted).
Solved, the problem was that by default Wireshark did not monitor any interfaces but after going to the configuration they became visible and I was able to start monitoring them, even on promiscuous mode.