So there has been some hearsay going around as of late about BWE access finally coming to Amazon preorders, but we haven't heard anything concrete yet regarding this. Well, I come here to tell you that it is absolutely true (unless Amazon is just trolling me). I noticed earlier that Amazon's product page for GW2 had been updated to say that a preorder included not only the 3 day head start, but also access to the beta weekend events.
I wasn't content with this being enough evidence, especially with the following wording found in that above image: "The code to setup your Guild Wars 2 account early and access Beta Weekend Events will be emailed at least a few days before the release of the game." I went ahead and grabbed a preorder, even though I have it prepurchased through Anet's website. Figure I'll just give it to my wife to try to pull her away from Tera. Anyway, shortly after placing the preorder, I received the following email:
Now while I can't verify this as meaning 100% for certain that $0 down preorders through Amazon will net you BWE access due to there not currently being a live event, this is about as much proof as we can get. So if you were on the fence at all about GW2, interested in checking it out, but didn't want to drop $60 to satisfy that curiosity, it seems now you can do so gratis thanks to Amazon.