One of the more interesting things about the Nexus S is that it has a Near Field Communications sensor, which could make some mobile actions, like code scanning, a lot easier and faster in the future. The Nexus S is the first phone to have it, but all the other phones that will have Gingerbread will also be able to support a NFC sensor.
I think Google, Apple and others will really push for this technology to become standard in the mobile world, so expect it to become useful very soon. Until then, check out this video below from AndroidCentral that explains how NFC works:
http://www.youtube.com/watch?v=LhFrAVKN7Dc&feature=player_embedded