Just recently, an exploit was found for iPhones. It is pretty simple to pull off and it can kill your phone. The exploit involves getting in the way of your phone attaching to some public WiFi signal, like that of Starbucks. Basically, they send a signal back down to your phone telling it the wrong date. Once this is done, your phone is basically a high priced brick.
To protect yourself, do two things. One, make sure to keep your phone updated. Apple is pretty good about patching issues...mostly. Second, use a little caution about which WiFi you connect to. Use your friend's but maybe not one from McDonald's or anything public unless you're phone is current with updates..
And since we are on the subject of Apple issues, go ahead and delete the software QuickTime from your computer if it is a Windows machine. Apple has basically disowned that software and it already has exploitable holes. So, be proactive and head to control Panels>Programs and Features>remove QuickTime.