Despite there being zero chance of Sony rolling out an official Ice Cream Sandwich (ICS) update for the Xperia Play, that doesn't necessarily mean you can't get your PlayStation-certified Play running the latest version of Google's Android OS.
Not when you have a community of industrious modders working day and night to get Android 4.0 (a.k.a. Ice Cream Sandwich) onto the handset through any means possible, anyway.
The latest (and by far the most promising-looking) ICS ROM for the Xperia Play comes from XDA developers forum user 'XDarkMario', whose XDark ROM features full support for the Play's slide-out controller. This offers a solution to the problem that many believe is the reason Sony cancelled the official ICS update for the Play.
According to Recombu, XDarkMario's ROM has been tested on a variety of Xperia Play games, including 9mm and Dead Space. It's also worth noting that the XDark ROM features a port of Sony's xLoud Engine and a variety of Sony widgets that ship with ICS.
The XDark ROM, which is based on Android 4.0.3, is currently at version 0.1, though version 0.2 isn't too far around the corner.
If you're not averse to having a tinker with your Xperia Play's digital innards, then the XDark ICS ROM is probably your best bet for getting Android 4.0 on your device.