iOS developer Ori Kadoshi has pushed a new Siri-related tweak to the Cydia store called Custom Siri Background. As the name suggests, the tweak simply lets you change Siri’s background wallpaper. You can choose any custom image or use a photo taken with your iPhone camera directly from the camera roll. Custom Siri Background is reported to be compatible with iPhone 4S as well as other iOS devices that have Siri installed (with Spire etc).
You can download Custom Siri Background tweak for free via the BigBoss repo.
Of course you will need a jailbroken iPhone 4S to install the tweak. Take a look at our step-by-step guide tutorial which will guide you through the whole untethered jailbreak process.