Sorry for necromancing this thread.
@MJ that's just link to API docs. I can't seem to find a way to get new developer key - so basically, API does not exist (at least not for new developers).
Post Reactions Plugin
I am searching for a post reaction plugin, so you have a few possiblities to give feedback to a post like
"Useful" "Promote" "Awesome" "WTF" etc you know the deal!
I can pay little bit for the plugin to develop if it is needed - please get in touch.
There have been a few requests, but I don't think any has made one yet.