Starting in August, all US passports will contain RFID tags that will hold all matter of identification information. The government hopes this will cut down on errors by immigration officials and counterfeit passports. This way well be the case, but RFID tags can be scanned or skimmed by criminals with the right equipment. You only need to be a few feet away from the subject as well, leading to so called contactless crimes. The State Department, of course, is confident they are secure, but as every geek knows, there is no such thing as 100% secure.
By the way, you should also be careful with your Bluetooth cell phone as well because it has been well established that it is pretty easy to hack a phone when Bluetooth is turned on, allowing someone to download all your contacts and other information. Especially if it’s a smart phone with notes. Don’t store any PIN information on your cell.