When I got my iPhone 3GS I desperately wanted to jailbreak it. I loved the concepts of a customized lockscreen and themes, and that is just the beginning. I want side-loaded apps, a break from Apple’s confusing , and sometimes ridiculous, rules. Apple has not taken a very aggressive approach, but nonetheless one of my main reasons for not jailbreaking is their policy.  The two things stopping me were the loss of warranty associated with jailbreaking and the occasional sluggishness of having a jailbroken device.