As we can see, iOS 5.1 didn't bring any Siri support for non-iPhone 4S devices and Apple don't plan any of those updates in the future. But jailbreak community never gets upset and comes out with another Siri alternative - SARA. This tweak was named one of the best Apple's voice assistant alternatives ever. The key difference is SARA's functionality. You can install this free Siri alternative on devices listed below:
SARA The Free Siri Alternative

 Sara Tweak supports following iDevices:

  • iPhone 4
  • iPhone 3GS
  • iPhone 3G
  • iPhone 2G
  • iPod Touch 4g
  • iPod Touch 3G
  • iPod Touch 2G
  • iPad 2
  • iPad

How to install SARA The Free Siri Alternative:

Step one: Before you continue make sure that you have jailbroken device running iOS 5.0, 5.0.1 or 5.1 SARA The Free Siri Alternative Step two: Go to Cydia, choose Manage tab menu, then Sources section, tap Edit and then Add button. Now type in this source field:
Step three: After adding this source to repo list choose it and you will see three packages. You need to pick package that is corresponding to your iOS device. The installation will automatically run and finish within a couple of moments, just wait. Attention: Console package should be used only for submitting error reports to SARA's developers. Step four: Once the installation process is finished you'll see SARA icon on your home screen.

Installing SARA The Free Siri Alternative manually.

Note: afc2add Cydia package must be installed on your iDevice before manually installing SARA Free Siri Alternative. Step one: Again, your device needs to be jailbroken and run iOS 5.0, 5.0.1 or 5.1 in order to install SARA. Step two: Now you need to download and install file-system editor for Windows or Mac OS X in order to manage your device. iExplorer of iFunBox would fit perfectly. Step three: Download SARA.deb file to your PC. Step four: When all the files are downloaded and installed open your file manger and proceed to:
Step five: Once in that directory, simply drop SARA's deb package you've downloaded earlier there. Step six: After package transfer is completed you'll need to reboot your device. After rebooting you'll see SARA icon on your homescreen (aka SpringBoard). Despite of what method you will use for installing SARA Free Siri Alternative, it should run perfectly and bring joy of using voice assistant on your non-iPhone 4S device.