Looks like the countdown has begun to the official Android 4.1.2 Jelly Bean firmware update for the Xperia S (LT26i). A new firmware version (6.2.B.0.200) has just been certified by the PTCRB, which is a slightly tweaked version of the leaked build that appeared at the end of April (6.2.B.0.197). Fingers crossed it will make an appearance by the end of this month.
Update: The Xperia acro S and Xperia SL Jelly Bean firmware has also been certified with the same firmware build (6.2.B.0.200).
Thanks Juha!