Amazon is not a reliable source for release dates. They are often wrong. But it is "odd" that they're saying something now, so close the date. We've previously heard a rumor that Nov. 2 might be another release date, and we know that Cataclysm is on track for a 2010 release, barring something nuts.
Until Blizzard announces the date itself, we don't know exactly when Cataclysm will be released. So until then, just grab a towel and don't panic.
And let me just make it real clear: WoW Insider is not claiming Nov. 23 is Cataclysm's release date. We're just reporting on what has happened with Amazon emails.