Apple, who has always been against jailbreaking, responded today about this new ruling. They say you can jailbreak, but it will still void your warranty. An apple spokesperson said the following:
Apple’s goal has always been to insure that our customers have a great experience with their iPhone and we know that jailbreaking can severely degrade the experience. As we’ve said before, the vast majority of customers do not jailbreak their iPhones as this can violate the warranty and can cause the iPhone to become unstable and not work reliably.I can see where Apple is coming from on this, but jailbreaking does not make your iPhone unstable and unreliable. I used to have a jailbreak, and sure, it lags a little bit, and sometimes apps crash, but most of that was a hardware issue since I have an iPod touch 2nd Gen. If jailbreaking was so much of a problem, then how come 10% of iPhones are jailbroken?
If you do need have a problem with your iPhone and it's jailbroken, simply hit the restore button in iTunes to restore to the official version of the firmware.