The rumors that were going around have been confirmed today by the official Sony blog that also came with details about the new features they were bringing to the phones.
Among the new features that Android 4.1.2 Jelly Bean update brings (the sleek Google Now and project Butter benefits), the stock Sony Media apps will get a new look. The Walkman, Album and Movies apps will get a new and improved UI (short for User Interface). Another improvement the update will bring are more personalization options. Now you will be able to have up to 7 desktop panes, auto-resizing widgets and other features.
Also on the list is the new app organization and search in the app tray that will enable you to organize your apps in folders right in the tray by dragging and dropping one app on the other, and look for local apps through the new search box.
The camera will also receive a functionality boost with the addition of a more intuitive viewfinder through the new auto scene setting. The camera app will also have a dedicated button to switch between the back-facing camera and the front-facing camera right without having to open the menu. These are just some of the phones that will receive the phone, but they mentioned that they will give the gift of Jelly Bean to the owners of other Xperia phones in the near future.
The availability of the updates for the three smart phones will vary by the country and carrier versions (as usual the carrier-branded phones will receive it after the service providers will get to tweak the update).
When it will become available in your region/carrier, you will receive a notification on your phone advising you to update your phone. This procedure will be possible through OTA in most cases, or the PC Companion or Bridge (in the case of Mac computers)