I hadn't seen this feature in any of the reviews or unboxing videos until I stumbled upon this one, and I'm not sure why. It incorporates a swipe gesture to quickly change between tabs and navigate the various browser menus, making one handed use simpler and overall browser use more fluid. Check it out.
(He uses it throughout the comparison but explains it at 5:45)
Galaxy Nexus VS iPhone 4S Browser Test! - YouTube
(He uses it throughout the comparison but explains it at 5:45)
Galaxy Nexus VS iPhone 4S Browser Test! - YouTube