The Sony Xperia Z is now receiving the Android 4.2.2 software update which is the latest version of Android 4.2 Jelly Bean. The Xperia Z with the C6603 model number which is the unlocked International version will be the first to receive the update, with the other variants to follow.You should receive a notification when the update is available for your unit, at which point you can initiate it. We suggest using Wi-Fi in order to avoid unnecessary data charges. You will also be able to update your device using the Sony PC Companion.
The Sony Xperia Z is the company's flagship handset which features a 5 inch full HD touch display with a Mobile BRAVIA engine, 16GB of internal storage which can be expanded through microSD, a 13 megapixel camera capable of 1080p HD video capture, a secondary HD camera for video calls and is powered by a 1.5 GHz quad-core Snapdragon S4 processor with 2GB of RAM.
If you are extremely eager to try out the update, you can consider installing a leaked image which you will find by following the source link. However the instructions to manually update are in Spanish, so you are advised not to continue unless you can understand the instructions properly.
source - Tutto Android