Chainfire announced the release of new CF-Root that can root galaxy nexus on Android ice cream sandwich 4.0.2. The root guide comes from XDA forums, a dedicated forum that provides guides and tutorials on rooting and unrooting android devices.
This rooted kernel is for the "rooting beginners" and those who want to keep as close to stock as possible. CF-Root takes the kernel from an original firmware, and just adds root and busybox. - XDA