With Apple announcing the new iPad 3 and iOS 5.1, and once again Siri being left out of the picture, it is unlikely that Siri will be making its way to any of the other existing iOS devices via any future updates either.
Siri for iPhone 4, 3GS and even new iPad 3
So if you’re hoping to get your hands on Siri then there is now another option. Earlier last month we talked about the i4Siri project. We mentioned how it was progressing well and that it would be out very soon. Well that day has come.
If you have an iPhone 4, iPhone 3GS or a new iPad 3, you will first need to jailbreak your device. Once you’ve done that, follow the step-by-step installation instructions at the source link at the bottom.
On a side note, Apple appears to be pretty critical about apps in the App Store that rival Siri so this may be your best bet at the moment.