Some Galaxy Nexus users who've recently updated their devices to Android 4.1.1 Jelly Bean have been experiencing issues with the phone's GPS capabilities. Specifically, some Gnex owners are unable to get a GPS fix, even with several satellites in view. It's a pretty nasty bug that, at worst, can leave you unable to track your location.
To check if you're affected, open up an app that constantly tracks where you are, like Google Maps, (and wait a while -- GPS takes time to kick in) then check the notification shade for a GPS message. If the text says "Searching for GPS..." and you're not seeing a flashing icon, that means you're not getting a GPS lock. To confirm that you're affected by the bug, you can download the GPS Test app and see if you have satellites within view.
Fortunately, there's an easy fix for anyone experiencing problems -- simply go to Settings > Location services, uncheck and re-check "Google's location service," and you should be good to go. We've confirmed that this remedies the situation on our own phones, and we've heard that it's worked for others, too. It looks like this is just a weird server-side glitch, and clearing and re-enabling Google location services resets things on the phone's side.
If you've been experiencing GPS issues on the Galaxy Nexus, let us know how you're getting on down in the comments.