A good move by amazon. They have created a wiki page for each of the items in their catalog. Research has shown that anything mentioned by independent sources about an item will increase customer confidence in that item. Even if the comment is negative.
Items with user comments on Amazon simply sell more. Many people read negative comments about a product or a vendor and simply dismiss it because they don't relate to the author. So if you can get people to say something about your product, anything really, it will increase your sales.
Customer comments are one way, wiki is another. They are complimentary.