An iPhone hacker who goes by Musclenerd noticed that the latest update leaves system files unencrypted which were previously encrypted. An article at Cult of Mac notes this makes it possible to enable Siri on older devices without using the legally questionable app already available for jailbroken phones.
Unfortunately it's likely this is the result of an oversight, rather than an intentional decision by Apple. The company is known for locking down their phones as tightly as possible.
Prior to phone jailbreaking being granted a DMCA exemption, their encryption was even used to make the practice illegal. Don't be surprised if the files are encrypted again in the next update.
Written by: Rich Fiscus @ 20 Dec 2011 3:21