Android 4.0 Ice Cream Sandwich is launched officially but it is available on the Samsung Galaxy Nexus only. So far, there is no announcement for the upgradation of other Android phones and tablets with the Android 4.0 Ice Cream Sandwich. But if you can not wait for that and want to have the Android ICS on your old Android phone as soon as possible then , here is something really nice for you.
You can have an Android launcher which is the exact copy of the Android 4.0 Ice Cream Sandwich GUI. This app is developed by the Syndicate Apps and it is available in the Android Market for free.
You can customize it and make it look exactly like the real Android 4.0 ICS. I have installed and used it on my Android tablet and it worked pretty fine. Below is a video given of the Android ICS Launcher working on the Android tablet.
Android 4.0 Ice Cream Sandwich running on Android tablet
Only issue is that it is designed for the Android phones, so few features will not work properly if you are installing the Android ICS launcher on a tablet. But still it is worth to try until you are not going to get the real Android ICS.
Install Android ICS Launcher