I'll do a post later about session hijacking, firesheep and the evils of non https based websites. In the meantime, if you use firefox be sure to the run the https everywhere extension. Without https everywhere I would be concerned about accessing my accounts on a public wifi network. HTTPS Everywhere forces the browser to use https when accessing any website that supports both http and https.
(By the way If you have a security question, or question on any of the topics I cover on my blog leave a comment and I’ll be happy to do a post answering your questions)