The latest firmware update for the Sony Xperia Z (SO-02E) is version number 10.1.D.0.333. This firmware brings two main features to the NTT DoCoMo handset. First of all, it fixes the Sleep of Death bug that has plagued some Xperia Z handsets, secondly it also adds the ‘White balance’ display calibration setting originally found in the Xperia ZL.
This gives a strong hint that we are likely to see it appear on western Xperia Z (C660X) handsets soon – hopefully in the next firmware update. There are, of course, mods that can be used to get it working now, but it will be great to see it officially supported.