Siri has finally been ported over to other iOS Devices and, unlike last time, there is a way you can install it right now,Though we DO NOT RECOMMEND IT.We suggest that you wait until @chpwn releases it.
How To Install Siri GUI On iPhone 4 and iPod touch 4G
Step 1: You should already be Jailbroken on iOS5.If you’re a beginner just leave a comment in the comment section.
Step 2: Download files required for the Siri port to iPhone 4 and iPod touch 4G. You will have to find these files yourself as we wont be able to share these files with you.
Step 3: Using a file explorer for your iOS device, copy over the AssistantServices.frameworkfolder you downloaded in Step 2 to Root > System > Library > PrivateFrameworks after plugging in your device to your computer via USB.
Step 4: Transfer all files from the Springboard folder in Step 2 to Root > System > Library > CoreServices > Springboard.app on your iOS device.
Step 5: Using iFile (you can get it from Cydia), open the .plist file for your iOS device fromSystem > Library > CoreServices > Springboard.app. It will be named N81AP for iPod touch 4G and N9x for iPhone 4 (where x may be 0, 1, 2).
Step 6: Add a new property list named assistant to the .plist file and set its class as Booleanwhile setting its value as YES.
Step 7: Add the following to the .plist file:
Step 8: Respring your iOS device.
If you followed the steps correctly, Siri’s GUI will be installed on your iOS device. You can hold the Home button to activate it. Once again, we remind you that voice commands don’t work yet since Apple’s servers don’t accept voice command input from iPhone 4 or iPod touch 4G.