As expected the update is bring rolled-out OTA, and will soon reach everyone. The ICS running Galaxy Nexus are getting a 147MB upgrade, while Android 4.1 running devices will get a smaller 8.50MB update.
On the other hand, even though there is still sometime in Nexus 7 to reach retail market, Google has pushed Android 4.1.1 for the tablet as well. The tablet is currently owned by the select Google I/O attendees. The update size for Nexus 7 is 12.6 MB and is also being released over-the-air.
You can manually download the updates from here and apply them using the detailed guide given at XDA.
For Galaxy Nexus:
takju-JRO03C-from-JRN84D (8,914,753 bytes)
takju-JRO03C-from-IMM76I (154,343,776 bytes)
The rollout of Android 4.1, Jelly Bean, begins today, starting with Galaxy Nexus HSPA+ devices.
Jelly Bean makes everything feel fast, fluid, and smooth. Notifications are expandable and actionable, widgets are magical and the keyboard is smarter and more accurate: http://www.android.com/whatsnew/
Jelly Bean also features a redesigned search experience, with a new user interface and faster Voice Search. You can type your query or simply ask Google a question. Google can speak back to you, delivering a precise answer if it knows one, in addition to a list of search results.
Google Now is also part of the updated Google app, getting you just the right information at just the right time. Google Now tells you today’s weather before you start your day, how much traffic to expect before you leave for work, or your favorite team’s score as they’re playing. There’s no digging required: cards appear at the moment you need them most.
If you’ve got a Galaxy Nexus HSPA+ device, you will receive a prompt alerting you to the update over the next several days. Up next for Jelly Bean: all Galaxy Nexus, Nexus S, Motorola Xoom and of course, Nexus 7, which will ship with Jelly Bean later this month.