Looks like another developer has come out and released, what he says, is a working AOSP built Jelly Bean ROM for the Samsung Nexus S. Since he has released it earlier today, a few fixes went into place like adding the camera app back in and offering up the Jelly Bean Google Apps. legolas93 says “All Works” and no bugs are listed on the OP right now. After cruising through some of the comments from people who are already giving it a go, most things seem just fine with a  few minor exceptions like camera effects.
Of course we don’t recommend a novice flasher tries to flash the build. Always make a backup and when in doubt, read the thread from front to back. If you are a bit curious and don’t mind taking a risk, you should jump over to legolas93’s XDA threadfor all the details and needed files. Let us know how it goes.
Via XDA