Yesterday, the CyanogenMod team announced the roll out of their official nightly builds of CM 10.1 for the Nexus 4. They also announced that the Nexus 10 will get it very soon.
CyanogenMod 10.1 is based on the newly released Google Android 4.2 Jelly Bean, and Nexus 4 being the first device that ships with Android 4.2 pre-installed has to get it first. This is the reason why buying a Nexus device always pays its debts.