Sony has promised Android 4.3 Jelly Bean updates for some of its Xperia 2013 devices starting in December 2013. It is now a firmware package is already available to those wanting to flash their Xperia Z and Xperia ZL. The leaked Android 4.3 updates for the Xperia Z and Xperia ZL are marked as "Commercial & Journalists" releases, which mean that it's not really intended for retail devices.

However, adventurous Xperia owners should flash the firmware into any international Xperia ZL (C6503) or LTE Xperia Z (C6603) using proper flash tools. While it's possible that this software build (version 10.4.B.0.569) will be the same to officially land through OTA updates before 2013 ends, there's no guarantee and caution is still advised.

Sony's most recent update advisory announces its plans to start updating the Xperia T, Xperia TX, Xperia V, Xperia Z, Xperia ZL, Xperia ZR, Tablet Z, SP, Z1 and Z Ultra in December 2013 but there's still no sign of Android 4.3 Jelly Bean based firmware for other Sony devices to date. A developer at the XDA forum has managed to get his hands on the Android 4.3 firmware for the Xperia Z and Xperia ZL.

Early reports from Xperia Z and Xperia ZL owners showed that the leaked firmware has a lot of enhancements and goodies. The first big difference from the older Android 4.2 firmware was the improvement in performance and speed. Other changes included a new single-handed keyboard mode, a white theme being used across the entire UI and a new camera app seen on Xperia Z1.

There are also a bunch of usability enhancements and new themes throughout the UI. Sony's suite of media apps were also updated with minor improvements and features. Unfortunately, there are still a few bugs, suggesting that this is not the final firmware.

If you are impatient and cannot wait for the official Android 4.3 update to arrive in your Xperia Z or Xperia ZL, you always have the option to flash the leaked firmware manually and enjoy the goodness offered by the most recent version, Android 4.3 Jelly Bean.