Is it? I think Google Now is part of the "Google Apps for Android" suite. These apps are not part of Android itself, they are licensed by manufacturers to complement their Android-based operating system.
And these Apps are usually updated by Google and independently from the OS. So unless "Google Now" uses a specific API that is only available in 4.1, I would expect older devices receive the app as well.
It's not an app... it's like the notification tray. You can't simply 'take' the notification tray from one OS to another. Same with this. It comes with Jelly Bean.
Is it? I think Google Now is part of the "Google Apps for Android" suite. These apps are not part of Android itself, they are licensed by manufacturers to complement their Android-based operating system.
And these Apps are usually updated by Google and independently from the OS. So unless "Google Now" uses a specific API that is only available in 4.1, I would expect older devices receive the app as well.