I'm pretty sure sniffing passwords on wireless networks is extremely commonplace. Just look at how many tutorials there are for it on the web from a simple Google Search - https://www.google.com/search?num=50&hl=en&q=sniff+passwords+wireless or Bing search - http://www.bing.com/search?q=sniff+password+wifi&go=&qs=n&form=QBRE&pq=sniff%2520password%2520wifi&sc=2-18&sp=-1&sk=

I'm pretty sure sniffing passwords on wireless networks is extremely commonplace. Just look at how many tutorials there are for it on the web from a simple Google Search or Bing search.