Earlier today, the Jelly Bean source code rolled into AOSP (Android Open Source Project). This is a big deal - one we've been waiting for since the great Google I/O unveiling. What does it mean exactly?
It means that ROMs that are built from AOSP, like CyanogenMod, can now start integrating the Jelly Bean code and release the first true JB nightlies. Not broken ports from the Galaxy Nexus builds - real ROMs. They can also work out bugs because they can see the source code.
Manufacturers can now start working on updating their devices to the actual Jelly Bean release - remember, Google was still working on the final touches to JB when they released the preview, so even OEMs didn't have what rolled out today.