Leaving aside the fact that Amazon's warehouse square footage is greater than the area of state of Delaware, I think Amazon is smart enough not to telegraph their future plans in such an obvious way. I don't think they've made that kind of mistake before, not with any of their launches.
What's more, the Kindle DX has gone on sale before. The last sale I can recall (for the new Kindle DX, not reconditioned) was during the Christmas season, right when you'd expect a sale. That's an important detail, because right now we're in the back to school period, which is another time you might see an expensive gadget go on sale.
Gizmodo is speculating that a complete refresh of the Kindle line is coming next week, and they're pointing at other sales today as proof. For example, there are quite a few Lightening Sales scheduled for today for unnamed accessories for the Kindle Fire and various Kindle models. I'm sticking by my previous objection. They're also pointing at the Kindle Touch 3G being out of stock as proof that a change is coming. That would have some weight, except that all the other models are still in stock. This could just be bad timing, not a sign of coming events.
Folks, I can give you a simple explanation for the sales today. It's not just that we're in the back to school season; I wonder if Amazon lined up these sales today just to get attention. They are that clever, you know, and if that was their goal it worked.
I'm not going to get excited about the possible launch of the next Kindle Whatever until the invites go out. I also wouldn't recommend the Kindle DX even though it is on sale; a similarly priced Android tablet would likely be a better deal.
There's a deal today on Ebay that Gizmodo seems to have missed. The K3 3G is listed for $120 (new), or $70 off retail. That's a very nice price and I think it reinforces the coincidence argument. Update: A reader pointed out that the K3 on sale was a special offers model, not the ad-free one. That makes it not such a great deal.