While it's not Android version update, a new firmware update is currently rolling out the waterproofed Xperia Z owners around the world. The update brings camera quality improvements and the Sony app White Balance.
Firmware version 10.1.1.A.1.307 can be grabbed over the air, and so far, reports are indicating that it is being pushed out in Belgium, Hong Kong, Spain, and a number of other hotspots. If the update hasn't hit your area yet, it can be downloaded through Sony's PC Companion. As with all updates, make sure the handset is charged, and if you're going to go the OTA route, tethered to a Wi-Fi connection.
Sony did not accompany the update with a list of changes, so what we know of the improvements comes from users testing the firmware out. Taiwanese website E-Price states that there is a bump in camera quality, showing off side-by-side pics. The site does state that the brightness is due to the shots being taken at different times of day, but there is a noticeable increase in the clarity of the picture.
The White Balance app allows Xperia Z users to go ahead and further customize the hue, white balance and saturation of the display. It won't fundamentally change the Android experience on the smartphone, but it will make viewing the screen easier on the eyes for some.
Let us know if you had a chance to snag firmware 10.1.1.A.1.307 for the Sony Xperia Z and any changes you notice in the comments section below.