The redesign was perhaps already underway when Nielsen's column appeared (Amazon changed the "Add to Cart" and "Buy with 1-click" button icon few weeks ago) but the latest change - that of doing away with the left bar seems inspired by Nielsen's write up. The space at left previously contained features such as, recently viewed items, 'listmania', 'So you'd like to...' guides and promotions of other Amazon sections unrelated with the product. Nielsen specifically mentioned this space and as always, used strong language to denounce the useless features.
Advertising on product pages. Amazon spends about two inches of each product page advertising other websites. Although this generates revenue, the average e-commerce site should be ashamed if it can't make far more money selling to a hot lead who's already investigating one of its own products.
Amazon has also redesigned product information area above the fold with a bigger product image, streamlined information and other changes. Compare screenshots of the product page from two months ago and the one reflecting the redesign as it stands now.
Go to this page on Amazon.com and see the changes for yourself.