If You Rely On Spire, Stay On iOS 5.0.1
Following the release of the iOS 5.0.1 untethered jailbreak, many rejoiced with the release of Spire, a simple Siri installer developed by iOS hackers Grant Paul
and Ryan Petrich
that could be used for installing Siri functionality on any iOS 5 iPhone, iPad, or iPod touch. In iOS 5.0.1, Apple made a mistake allowing hackers to exploit a cache file for gaining access to the files necessary for making Spire a reality.
Although we have a tethered jailbreak for iOS 5.1 at this time for non-A5 devices, you will notice that Spire cannot be installed on iOS 5.1 as Cydia will not allow you to. This is because iOS 5.1 does not support the iOS 5.0.1 version of the frameworks, but alternatively only supports the iOS 5.1 version of the frameworks. The iOS 5.0.1 frameworks were easy to exploit as Apple handed the files to us on a silver platter, unencrypted, and made it very straightforward to create an automated downloader for them.
Citing Ryan Petrich, it is extremely likely that we will not see a Spire Siri installer for iOS 5.1 whether our jailbreak is tethered or untethered because writing the installer would be less straightforward and much more difficult. That being said, if you are on iOS 5.0.1 and happy with your untethered jailbreak and Spire Siri functionality, you may not want to upgrade.
Those of you that don’t use Spire for any part of your daily lives, probably won’t have to worry about upgrading to iOS 5.1 or any newer firmware for that matter when a newer jailbreak for the corresponding firmware is released. Hackers are actively working on finding exploits for Apple’s newest firmware, iOS 5.1.
Sources: Ryan Petrich