By now, any sentient IT person knows the perils of open Wi-Fi. Those free connections in cafes and hotels don't encrypt network traffic, so others on the network can read your traffic and possibly hijack your sessions. But one of the main solutions to this problem has a hole in it that isn't widely appreciated.
Large sites like Twitter and Google have adopted SSL broadly in order to protect users on such networks. But for broader protection, many people use a virtual private network (VPN). Most people, if they use a VPN at all, use a corporate one. But there are public services as well, such as F-Secure's Freedome and Privax's HideMyAss. Your device connects with the VPN service's servers and establishes an encrypted tunnel for all your Internet traffic from the device to their servers. The service then proxies all your traffic to and from its destination.
It's a better solution than relying on SSL from websites for a number of reasons: with a VPN, all of the traffic from your device is encrypted, whether the site you are visiting has SSL or not. Even if the Wi-Fi access point to which you are connected is malicious, it can't see the traffic. Any party that is in a position to monitor your traffic can't even see the addresses and URLs of the sites with which you are communicating, something they can do with SSL over open Wi-Fi.