I personally called Apple Care and talked with one of the Apple Care Specialists. I asked him if jailbreaking was illegal. He replied back with, "No. Jailbreaking is not illegal, but Apple doesn't recommend it." With a little explaining he told me that if your iPhone has any software, and/or hardware faults, and they see that it is jailbroken, tough luck. They won't help you. Hearing that led to the question does jailbreaking void your warranty? What I heard was actually suprising. He told me that jailbreaking can void your warranty if it is jailbroken and Apple sees it, and records it. He told me you can still jailbreak, and restore your iDevice and you will have your warranty back on it again.The suprising part was that he said he has actually jailbroken his iPhone before, but doesn't now because he has the iPhone 5.
So there you have it. Two of the most commonly asked questions about jailbreaking answered from an Apple Care Specialist. If you want to find out your self feel free to contact Apple Care 1-800-APL-CARE (1-800-275-2273).