Nexus S was shown during a Web Conference with Eric Schmidt from Google. However, the phone brand was masked out although those leaked pics suggest it could be Samsung.
Apparently, Android 2.3 (Gingerbread) is almost ready to roll out (in the next few weeks), it seems that Google is focused on support for interacting with NFC-enhanced devices and RFID tags. In short, you could possibly use your phone as a credit card.
And on top of that, it seems that Nexus S might be rolling out at the same time as Android Gingerbread.