The Xperia Z (http://www.gsmarena.com/sony_xperia_z-5204.php) is one of the hottest devices in January, but unfortunately runs Android 4.1 Jelly Bean, and not the latest available version of the Google OS (which is 4.2). Sony, however, is going to make things right 'soon after the launch' of its 5" smartphone and update the smartphone to the latest Android version.
(http://st.gsmarena.com/vv/newsimg/13/01/xperia-z-4-2-jb/gsmarena_001.jpg)
This was confirmed by a Sony representative, who released the information in a recent Q&A session. When asked whether the Xperia Z will get Android 4.2, he said:
Xperia Z launches on JB 4.1, but will receive 4.2 shortly after launch. As always, we