XDA member itsmikeramsay has released unofficial CM10.1 ROMs for Galaxy S3 owners on T-Mobile and AT&T handsets. Whilst there are still some bugs to be worked out, it's a great start for users looking to run Android 4.2 on their S3.
Android 4.2-based CM 10.1 for Galaxy S3 and Xperia T teased, to reach nightly status soon
We’ve known for a while that CyanogenMod 10.1, based on Android 4.2 Jelly Bean, is a work in progress. However, seeing as the first ports for Nexus devices have only been made available this past week, we would have never suspected other builds are very close to reaching nightly status.
CyanogenMod 10.1 nightlies now available for Nexus 10
So you've unlocked and rooted your Nexus 10, but you're thinking you need more. If that previous sentence describes you, you'll be happy to know that the first CyanogenMod 10.1 nightlies are now available for your Nexus 10.
CyanogenMod 10.1 nightlies now available for the LG Nexus 4
If you happen to be a fan of CyanogenMod and are willing to live on the edge in terms of ROMs, there is now a CM10.1 nightly build available for the Nexus 4. In addition, a similar ROM is also being worked on for the Nexus 10 tablet.
CyanogenMod 10.1 progress is moving along, but the end result is still not near ready for release
While CyanogenMod 10 has recently come available as a stable release (for select devices), we are already hearing talk of the 4.2 merger -- CyanogenMod 10.1. Except while there is talk and there is progress being made, a recent status update suggests any availability is still some time away.
CyanogenMod 10.1 (Android 4.2 Jelly Bean) is in the works, no ETA on release yet
Now that Android 4.2 Jelly Bean is officially out, we can’t but wonder what the first non-Nexus devices that will receive the update will be. We’re definitely not going to be surprised once we see CyanogenMod 10.1 roll out, even in early releases, for various Android handsets, but the CyanogenMod team can’t offer you a launch date estimate yet.