Install Siri On iPhone 4/3Gs, iPad And iPod Touch

Compatible Info :
It Will Only works on Jailbroken 5.0 or 5.0.1, 5.1 and on Following iDevices:
iPad 1
iPad 2
iPhone 3Gs
iPhone 4
iPod Touch 4G


Steps To Follow :
Step 1 – If you have installed Siri ports then Uninstall all.
Step 2 – Now Install the Spire from the big boss repo and Reboot after installing.
Step 3 – Now Go to the settings app/general/siri/ then Turn on.
Step 4 – Now Go to Settings/Spire/ and then in the Proxy url Input  
https://superbeta.chickenkiller.com
Step 5 – Now Go to the  
http://i4siri.com/installcertificate.html 
in iPhone Safari and install It .
Step 6 – Reboot .
Step 7 – Start talking to Siri and Make a Siri request.
Done !
You Can Get More Info From - i4Siri Blog

Source : http://justtipsandtricks.com/how-to-run-install-on-iphone-43gs-ipad-and-ipod-touch-i4siri-released/