One of the hottest features of Android 4.1 Jelly Bean is Google Now – Google’s (Siri like) voice assistant which helps you manage your device. While the app is currently exclusive to Jelly Bean developers have managed to hack it to work on Android ICS and now on any Android device with an ARMv7 processor.To be able to install this modified version of Google Now your device will have to be rooted using ClockworkMod recovery, and have an ARMv7 processor. You can check if your device is compatible by comparing against this (partial) list of supported devices here.
source – XDA Developers