The CyanogenMod crew got it to the nightlies for a couple of the most popular Android devices out there, and in record time after Google released the Android 4.1 Jelly Bean
source code at that.
The guys are now offering CM10 nightlies for the following handsets:
# The US SGS3 variants
# The Galaxy Nexus variants
# The Nexus S varaints
# The Nexus 7
# The Transformer and Transformer Prime
# The SGS1 variants (Vibrant, Captivate, International, and i9000b)
# The SGS2 i9100g
# P3 and P5 tablets
CM9 builds for those devices that don't get a CM10 one at the moment will continue, but on a weekly basis, in order to thoroughly go through bug fixes and such.