The Android 4.1.2 Jelly Bean firmware update(9.1.A.0.489) has started to roll out for the Sony Xperia T (LT30p).
According to Sony Xperia Blog , the firmware is the same that was certified i.e. version number 9.1.A.0.489 and runs on the 3.4.0 kernel. But not sure exactly which regions have the update, but it appears to be live in the Netherlands at least.
Update includes Google Now, Project Butter, improved notifications, etc., along with Sony’s own changes.