Sony Mobile has its own way of releasing Android 4.0 ICS updates, so Xperia users may want to pay close attention to what version of the update they are trying to flash.
It appears that the Japanese company launches ICS updates for each country and carrier that the Xperia model belongs to, so it usually takes some time until all users are getting the upgrade.
Today, the company published the list of available updates for Xperia U, sola and go smartphones. You will need to check out the SI number of your device before downloading the update.
The SI number is found behind the battery, but if you cannot find the same number on Sony’s list you will have to check back later as the handset maker regularly updates it. You can find more info here.