Symantec published a paper in conjunction with Indiana University describing how attackers could be using unsecured home wireless access points in pharming attacks. The vulnerability is related to easily guessed credentials on the wireless routers and default installations are definitely easily guessed.

The ploy described in this paper ( involves the use of javascript on a malicious website that changes the DNS settings on the wireless router - provided the router credentials can be guessed by the application.

So, there is more to it than being sure your wireless transmissions are encrypted.