The recently certified firmware build 14.3.A.0.761 for the Sony Xperia Z1 has been released into China. The Xperia Update Checker shows that the update has so far only hit the C6902 Xperia Z1 model running China firmware. There is no changelog, but the update is only likely to offer bug fixes over the previous 14.3.A.0.757 firmware. The update should start hitting other regions shortly.
Via XDA-developers.
Thanks Bruno!