Currently 6 out of 30 links on HN are Amazon links, 4 of them in the top 5. Looks like someone paid for placement.
How was this different from when Apple anncouned new iPhones, iPads and Apple TV's last month? Or when Google announced the new chrome cast and music streaming device? Both were at the top on their respective days and discussed ad nauseam in the comments.
It's not. I'm not sure why you're asking this.