Update: The Nexus 7 2013 build (codename "Flo") has now been posted. It's the first official CM build for the new Nexus 7.
ROM addicts, the time has come. The CyanogenMod team has been working diligently on version 10.2 of the popular ROM family, the Android Jelly Bean 4.3 update. Tonight the first batch of nightlies are being posted to the download page, Get.CM. There are only a few devices with updated builds at the moment, but that should change as the night progresses. The build boxes are pushing out device files as fast as they can.
Unfortunately, not all of the officially supported CyangoenMod devices will be getting version 10.2 right away. According to the announcement post on Google+ there will be a few stragglers, but presumably the plan is to get everything updated eventually. They didn't say which phones or tablets would be left out. At the time of writing, there are only six builds up: the Galaxy S Relay 4G for T-Mobile, the Samsung Captivate for AT&T, and the AT&T, Sprint, MetroPCS, and Cricket versions of the Galaxy S III. Builds will be posted in alphabetical order based on their manufacturer/CyanogenMod codename. They're coming in fast, so keep an eye out.
As always, you'll need the Gapps flashable ZIP if you want access to the Play Store - the
current version for 10.1 should work with the nightly builds. (Update: looks like there's a 4.3 version of Gapps available.) That said, it's always best to have a backup of your current ROM handy in case anything goes wrong. Check the list on the right of the Get.CM page to get a rough idea of when your phone will come up (if it's included in the initial batch), and if you don't know the codename, poke around the wiki to find it. Happy flashing, ladies and gents.
Source: CyanogenMod Google+