The http://www.android.com/about/ice-cream-sandwich/ page details that Android 4.0 "Ice Cream Sandwich" introduced two interesting features for Camera: “continuous focus” and “zero shutter lag exposure”.
Have both of these features been removed or disabled post 4.0? My Galaxy Nexus seems to have neither since the 4.1 and 4.2 over-the-air upgrades.
Holding a 4.2 Galaxy Nexus still and taking a picture with auto settings and without flash in a relatively-very-well-lit nightclub takes about 3 seconds, and taking another picture right away takes another 3 seconds, seemingly indicating that both features are completely absent in stock 4.2.