Facebook Subscribe button or "How FB copies Twitter"

Apparently Facebook is trying to become more similar to Twitter, his competitor.

Indeed FB introduced the "Subscribe Button" that permits to follow the statuses and the pics of celebrities and people we admire but we are not (FB) friends of.
And this is kind of exactly what Twitter does, isn't it? Twitter permits you to follow posts, photos and links of people you don't know directly and also of people you know.

Now the question: How Twitter will react to this?