Sony has started pushing out a new update to several of its Xperia branded devices. It is basically a maintenance update that carries a build number of 1.1.A.0.1 and weighs in at 1.3MB. Sadly, not much is known about the update at the moment, including what exactly it brings along and which Xperia devices are getting it. Several users who've received it are reporting higher battery drain post-update. Via
Source: http://www.gsmarena.com/mystery_update_hitting_several_sony_xperia_devices-news-21138.php
