We work hard to ensure each of our products has the optimal user experience and therefore some products will remain at their current version of Android. In general, devices with 512MB RAM or less will not be upgraded to Android 4.1. As we identify other devices that will not be upgraded, we’ll provide updated information.
Of course this doesn’t mean you’re stuck with your current version; you can always root your device and flash a custom ROM based on Android 4.1 if it is available, but that will take some technical know-how which means that it might not be for everyone. In any case that’s the situation as it is for now, but check back with us from time to time as we’ll keep you in the loop.