I use FB occasionally, but I see this as much more like the <3 on Tumblr. If I <3 something, it means I've read it and I can find it again. If a post has 10k <3s I know it's probably something I should check out, which reminds me more of Digg or Stumble Upon than FB.

So yeah, basically, this is a feature lots of other sites have, and it's way more useful on some of them than it is on Facebook, and I'm in favor of that.