With the Takju variant of the Samsung Galaxy Nexus received Android 4.2 last week, it’s now the Yakju’s turn. To be specific, this 4.2 update is for the international version of the Galaxy Nexus not purchased in the Play Store and you should be running build JZO54K as a prerequisite before updating. Along with the 4.2 update, Google was also nice enough to provide the factory images to go along with the update. The OTA should be hitting applicable devices soon, or you could always try to fetch the update yourself via setting/about phone.
source: Google Devs