i for one think this is brilliant. we really need the ability to capure “meh” and “dislike” as well as “like” on the social web. jus looking at the number “likes” versus number of hits to an article is not enuf, imho. actual numbers provides a deeper understanding of your demographic and reader base.
besides, sometimes “meh” or “dislike” or “hate” “this-is-just-dumb” says a lot more then just walking away.
also more and more groups are now cropping on facebook with titles like “i really hate XYZ” and it’s membership base growing by people “LIKING” it …
instead, i feel/think, if we just had the ability to dislike something and just share that dislike instead of liking a negative statement user engagement would be easier

Facebook are already monitoring every aspect of your behaviour already. What would they gain from encouraging negative feedback? It reflects badly on a site where most of the content is spam and junk.