Getting tired of running the stock OS on your Xperia Ion? If so, official CyanogenMod nightlies are now available for the device (codenamed aoba). The first CM9 build hit get.cm just a bit ago, so you're only a download away from having one of the smoothest, best supported AOSP ROMs on the planet.
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.