CyanogenMod team has announced that it has begun rolling out CM 10.2 nightlies for select Android devices starting today. The first batch of nightlies can now be downloaded from get.cm.
At the time of writing this post, CM 10.2 nightlies for some Galaxy S III, Galaxy S and Galaxy S II variants, Optimus G, new Nexus 7 were available. More devices are expected to be added in the next few hours and coming days.
In addition to CM 10.2, you will need flashable Gapps Zip for Android 4.3, which can be grabbed from here.
CM team had also revealed recently that work on CM 10.1 will go on for some more time until they release the stable version of CM 10.1.3, following which there will be code-freeze for development on Android 4.2 based CM 10.1.