On Facebook you can click "like" on someone's status, or comment, or note, or picture. Just about anything. It's nice in some situations where you want to show that you appreciate whatever it is without saying "Haha!", "Cool!", or "Wow!" again...or whatever other one word would fit the situation...unless it really requires that...sometimes it does. The other alternative being to not say anything at all and simply enjoy it and laugh to yourself. But what's the point in that? Shouldn't someone know that you like what they wrote?
But on a blog? Someone took the time to write a whole post. There's a place to comment. Do we have to cut out that form of interaction? It's part of the fun of blogging, to actually hear what people think about what you wrote, and what they have to add to it. I don't even mind a "Haha, that's funny!" comment. It's still a comment, it's multiple words. But now there's this: http://buzz.blogger.com/2008/11/reactions-easily-engage-your-readers.html
"With Reactions, readers can easily respond with one click, increasing feedback on posts."
Okay...so you might get more feedback. (Anonymous though...) But I like real comments. I don't mind "like" on Facebook, but I don't want it invading my blog. And it's not going to, because I'm not going to add it. :D