It might be a small change but businesses and brands may find this useful when they're monitoring the performance of their wall posts. When you go into Facebook Insight on your brand page, you can now monitor how much negative feedback each of your posts receive.
Originally spotted over at Wisemetrics, underneath the analytics graph are a list of all your recent posts, and by clicking on the 'engaged users' section, you can see how many people clicked or shared your post.
What's interesting about this section isn't the main status but what's underneath it: the negative feedback that particular post has received. What Facebook Insights define as 'negative' are those posts which were either hidden in a person's news feed or gave it negative feedback in their news feed.
Admittedly, it's not a detailed analysis, but it gives an idea as to what direction Facebook are taking their analytics feature. If developed further, it will give page owners a whole new insight as to how well or badly your fans respond to your posts, but lets hope that they're planning on developing it further and that it isn't just a tacked on feature.