It seems that the CyanogenMod team is on a roll with Sony devices. Just yesterday the first nightly turned up for the Xperia ZL, and today the Xperia Z and Xperia V are joining the ranks. We know the two phones can survive water and boiling soup, but thanks to CyanogenMod, they will now survive the test of time with the latest versions of Android.
Definition: A "nightly" is a bleeding edge release that is built on a daily basis, usually at night after a full day's worth of new code has been committed.
It could oftentimes be unstable and not properly tested, lacking any changelogs, but eventually evolving into alphas, betas, release candidates, and finally stable releases.