I'm talking about apps that allow you to post things up on Twitter or Facebook from data you generate in the app (i.e. high scores, achievements, or results). We put this into our How Am I Feeling? app but very few people seem to be using it - at least that I can see anyway as I can only track on Twitter. What makes you want to announce what you did? Is it entirely an afterthought or just something you try once or twice and then forget about?