Reuters reports that the Google admits that its Street View vehicles captured much more WiFi data than previously reported. It appears that they managed to capture entire emails and passwords among other information. People are vilifying Google about this, but I am not going to get on that bandwagon. The reality is that they did this accidentally, but the architecture of WiFi allows any bad guy to do the same thing intentionally. Google did not "hack" in to these WiFi communications, they simply configured their WiFi cards to accept all packets flying by them through the air in the clear. Anyone sitting in a Starbucks, driving around town with a laptop in the passenger seat, or in a thousand other ways could intentionally capture and maintain much more information and with it do significant damage.
The take away from this is that you need to take precautions when using open public WiFi. Full VPN technologies like Anonymizer Universal ensure that when (not if) someone sniffs your traffic they will not be able to get any of your personal information.
One of the reasons interception of insecure passwords is so scary is the tendency for people to use the same passwords for many accounts. While you might not care if someone hacks in to your social network or news account, if you use the same password attackers might use it to log in to your bank or email.