Looks like the Android 4.2.1 update is rolling out soon http://benjaminkerensa.com/2013/01/15/sprint-to-start-rolling-out-android-4-2-1-to-galaxy-nexus
Hopefully an OTA goes out soon but im sure you can find root-free instructions someplace...
There won't be any root free instructions, it's won't pass md5 matching for an update.zip, and in order to flash via custom recovery, you need the phone to be rooted. Like CNET states, the update is around the corner, sprint knows it leaked, therefore the normal 2 week average might be shortened and an OTA will be pushed shortly.
Actually... There are lots of root-free directions floating around right now. I am neither rooted or unlocked and I am currently running 4.2. I don't plan to root until I have to but I have done it on previous phones. The directions for updating to 4.2 are only as far away as a Google search and once you have all the files and drivers you need it takes about 5 minutes to apply.
I like your way of stating your rooted, lol, i don't care sprint knows anyone who buys a google branded device will root. I've been rooted and running 4.2.1 since the day it leaked, Just that this being my first google nexus and understanding how the updates come from google just have to be sprint approved, i didn't think it was possible. Tried many times on many handsets in the past.
Sprint users on other forums are reporting that they are receiving 4.2.1 OTA on their devices today. (using the google services framework trick).
I haven't received it yet, but looks like today is the day we get the official OTA to 4.2.1
Hopefully, Sprint will get notified about this update sometime soon too