Amazon starts tagging

As reported by news.com, Amazon tries its hand at tagging. It's interesting to see if and how this will catch on at Amazon. Amazon already does a pretty good job of organizing their content. It's why I consider it a good example of an ergonosphere, if not the ergnosphere. So the question is, will Amazon users feel motivated to enter tags when Amazon already organizes their offerings for them? Maybe they will, after all, tagging is a very low-cost activity.