There's no explanation for why this took so long, but earlier today several blogs reported that Nook, Kindle, Google Play Books, and other ebookstores are no longer pricing ebooks at the publisher-mandated retail.
Curiously enough, Amazon is still reporting that the titles are still selling under the agency price (example). I have no explanation for that, but I suspect it is simply a bug. On a related note, I have learned that the RH titles will be sold under the wholesale model starting some time later this month.
I've checked the first few dozen titles listed here, and Amazon has almost always had the lowest price. They've marked most ebooks down 5% to 15%, with a few popular $15 bestseller ebooks marked down to $10.
Barnes & Noble has matched Amazon's prices across the board, and Google Play Books has matched Amazon's price on most titles. Kobo and Sony haven't lowered any prices just yet; they're still charging full retail.