Basically, what jailbreaking does is it allows you to use these two devices at their full potential, and helps to unleash their full capabilities. You can really customize them like crazy through jailbreaking, and it makes them more personal. It just makes the iPod Touch and iPhone that much more useful. It also allows you to download lots of free applications. An iPod Touch and iPhone would be pretty boring without a jailbreak, and thankfully it's legal.