Eric Schmidt said at the Web 2.0 Summit that Android OS 2.3 (Gingerbread) will be coming in the next few weeks. There is a chance that Gingerbread will be announced within the next 2 weeks, because Andy Rubin is going to attend the D: Dive into Mobile conference on December 6th, where he's expect to talk about the new Android - we hope the NEW version of Android.
Of course this doesn't really mean anything. After all, it's not like the D conference was set after Andy Rubin's schedule. He might just be invited there for a regular interview, and I think if Nexus S is not launched by then, he won't talk about Gingerbread at the conference either. He might give some more hints, but I doubt we'll see it then if it's not announced before the conference.
It's getting real close to Christmas, so hopefully both Google and Samsung are hurrying up with the supposedly dual-core Nexus S phone.