Spire the Siri port for non-iPhone4S Apple devices is sadly no longer developed and would even refuse to install on Apple iOS 5.1 . While trying to install via Cydia you will receive the following error. However, there is an alternative way to get this on iOS 5.1 as shown ahead.

It was just a matter of time after Apple made the decrypted ramdisks available with newer build of iOS 5.01 for legal Siri ports to appear, and that time has now come with popular iPhone dev @chpwn releasing the first legal port for "Siri" via Cydia. Dubbed "Spire" the legal port allows hackers to get required Siri files legally (gets downloaded from Apple servers) on older devices like iPhone 3GS, iPhone 4, iPod Touch 3G, iPod Touch 4G etc.