The Sony Ericsson Xperia Arc S is now receiving the Android 4.0.3 update, which is one of the latest versions of Android 4.0 Ice Cream Sandwich.Note that the update may not be available on your device immediately as it is released at different times depending on the operator and country.
NOTE Sony wants their users to note that upgrading their devices to Android 4.0 ICS may result in the device performance being affected. This is due to the ICS hardware requirements being more advanced that previous software updates.
In order to update to ICS you will have to connect your phone to your computer using the Sony PC Companion software for PC | MAC
Learn more about the Android ICS update for your device here.