Earlier today Google released the Android 4.1 source code into AOSP (Android Open Source Project), as noted by JBQ in the usual Android Building group. The release is Android 4.1.1, build JRO03C and will no doubt be the version that is pushed later this month over the air to Galaxy Nexus and Nexus 7 devices as outlined at Google I/O. Other Google Experience devices will get their update push later, including the Xoom and Nexus S.
Also among the things changed today is renewed AOSP support for the Verizon Galaxy Nexus with CDMA/LTE, codename "toro." Previously AOSP support was limited due to the presence of a proprietary rotation sensor by Invensys and CDMA/LTE binaries for provisioning on Verizon. JBQ notes that Google can now distribute the binaries required for the CDMA/LTE Galaxy Nexus. Note that the Sprint "toroplus" Galaxy Nexus is still not an AOSP-supported device.
Factory images aren't available yet for the Nexus devices, but will no doubt pop up in the usual place after the OTA push begins later this month.