The only way to get Jellybean as of now, unless you got your Nexus from Google I/O, is to root your device. Once you do root it though, after installing JB, you can remove your root access and use it just like stock JB. If you need any help, let me know. It doesn't take longer than 3 minutes and you'll be good to go. I got my Nexus last Thursday and within 5 minutes, I was running Jellybean on it. I'd be happy to help you experience the buttery, Jellybean goodness. Everyone should experience it.
Sent from my Jellybean'd Galaxy Nexus using Tapatalk 2