Google today posted factory images for Android 4.2.2 (JDQ39) for the Verizon Galaxy Nexus alongside the new 4.2.2 binaries.   If you are wondering what's the purpose of the factory images, they allow you to flash your phone back to its original stock state. This is really useful in the unfortunate event that you mess something up trying to install a custom ROM.

If you are on a Sprint Galaxy Nexus, an Android 4.2.1 factory image is available as well.

Link: Verizon Galaxy Nexus (mysid) |  Sprint Galaxy Nexus (mysidspr)

Google has posted the factory images and binaries for the Nexus tablets and smartphone versions out there.  In case you haven't updated your Nexus devices to the newest Android 4.3 version, you can get it as follows:

• JSS15Q is available for the Nexus 7 (2013)
• JWR66Y is available for the Nexus 7 (2012), Nexus 4, Nexus and Galaxy Nexus (yakju and takju variants)

The Galaxy Nexus 4, Wifi and HSPA Nexus 7 (2012), Nexus 10 and GSM Galaxy Nexus all stick with build number JWR66Y and are referred to as "android-4.3_r1.1", while the Nexus 7 (2013) splits to a different path with build number JSS15Q and "android-4.3_r2.2". Sprint and Verizon versions of the Galaxy Nexus, along with the Nexus S, are seeing no factory image changes however.

Source: Android 4.3 download