The Wizards of the Coast website still lists November 19. I do have a guess about what happened...
Amazon third-party sellers who use Amazon Fulfillment are eligible to be listed as the default purchase. This is how Amazon is able to sell "hobby store exclusive" limited edition covers - it's technically not Amazon, they're just doing fulfillment for a third-party.
Like say I own Abstruse's Games and Stuff and I want to sell on Amazon. I sign a deal with Amazon to do the fulfillment so that products I sell on Amazon get Amazon Prime shipping and whatnot, but also my products can be listed as the default when someone clicks on the item. So if you go to order the Player's Handbook and Amazon's copy is $25 while mine is $24, my copy is the one that will show up if you just click to order and most customers will never know.
So my guess is some third-party seller updated their page today with both the Eberron sourcebook and the D&D Essentials Kit (which actually does release to mass markets on September 3) and mixed up the dates. It'll probably be fixed in a day or two.
Side note: This is why you'll see release dates on Amazon for pre-order books from companies like Fantasy Flight or Catalyst Game Labs who never announce firm release dates for physical products until the books are in the warehouse ready to ship. Some game store put their best guess up there because they had to put in something, or they're using the date they themselves got from their distributor (who either has more information or also just made up a reasonable date).