CyanogenMOD custom Android firmware is the most popular third-party Android ROM and been source of many Android Ice Cream Sandwich build. It took CM developers few months to cook the CM 9 – the Ice Cream Sandwich though the build was already been released at XDA and now the release candidate or RC1 is available for download.
CM 9 now supports 50 devices both smartphone and tablets like Samsung Galaxy S II and its variants, LG Optimus, HTC Sensations, Asus Transformer and its variants, Motorola Xoom, Samsung Galaxy Tabs, Sony Xperia Play and the HP Touchpad. Expect more supported devices in coming months. CyanogenMOD developers insures that the core of their operating system is stable and expect more nighties to come as new bugs are being discovered and hopefully a stable version will be released for public who is afraid of flashing their devices over and over. Another best way to get rid of any nuisance is to have ROM Manager Premium service where your nightlies update will be avaialbe to you ; no longer need of full download of the OS.
I know that CM fans were already been testing the build especially for the Galaxy S II and if your device just got the CM 9 treatment go over to CM 9 download page and choose your ROM.
The Ice Cream Sandwich is by far the longest version of Android to get into devices built from Gingerbread era. Tomorrow we might able to get glance to the new version of Android. The Android Jelly Bean 4.1.
As time of writing I am downloading the Galaxy S II CM 9 ICS ROM and will be installed probably tomorrow evening when I am free of any errands.
Resources and further reading:
Cyanogen Wiki
List of Cyanogen Mod 9 supported devices