Sony Ericsson officially confirmed that the first 2011 Xperia smartphones will be upgraded to Android 4.0 starting from end March/early April 2012. The first smartphones to get the upgrade are Xperia arc S, Xperia neo V and Xperia ray. Soon after, starting from end April/early May, Xperia arc, Xperia PLAY, Xperia neo, Xperia mini and mini pro, Xperia pro, Xperia active as well as Sony Ericsson Live with Walkman will get their upgrades.
Xperia smartphone owners will receive a notification in the phone instructing them to download the software over the air via 3G or WiFi. Alternatively, they can connect to a computer and download it via PC companion.
Source:- Sony Ericsson Blog