As pointed out by Android engineer Romain Guy on Twitter (the same engineer who posted that incredible Galaxy Nexus-shot 1080p video), Android 4.0 will support the ability to connect USB devices such as a controller or gamepad (or hard drive). While USB hosting was introduced in Honeycomb, Ice Cream Sandwich will certainly bring it to the masses and just about every Android phone going forward (every phone running ICS, anyway).
Guy notes if you put USB gamepad support together with the HDMI out featured on the new Galaxy Nexus (and perhaps many other devices in the near future), you end up with a pretty decent portable gaming console. This is especially true considering all of the great emulators available to Android users. The image below comes via Phandroid who pulled up this screenshot from Reddit related to pairing a game controller from the recent Ice Cream Sandwich SDK.