Jelly Bean has been out for little over a month now and came almost immediately to every Nexus device (besides the original Nexus). Now these really only matter to people that hack their Nexus devices and fear that one day they might brick their phone/tablet. The factory images have been released by Google for the Nexus 7, Nexus S (sojua or soju versions), and the Galaxy Nexus (yakju and takju versions). These are google to keep in a safe place just incase there ever comes a rainy day in which you may need them. Find the download link below.
Factory Images: Download from Google