Latest update hitting multiple models in different markets around the world.
Coming in just fashionably late behind its sibling the Xperia ZL, the Sony Xperia Z is receiving an update to Android 4.2.2 starting today. According to reports from users to XperiaBlog, the update is rolling out to several different regions already for the C6603 LTE model, and in Taiwan for the C6602 HSPA+ model. While the official support page hasn't been updated to reflect the newest build, the build number is reportedly the same 10.3.A.0.423 as the Xperia ZL. If you have your hands on an Xperia Z, you may want to download Sony's PC Companion (or Bridge For Mac) for the earliest shot at the update.
This also leads to a few questions about what version of Android will land on the Xperia Z when it hits T-Mobile in short order. Let's hope it's the same updated version as is rolling out worldwide today.