Yeah, participation from any kind of passive teasers or pushed content is a lot lower than you'd think. If we launch a new project and post a teaser about it on our very homepage, it's a coup if we get a 10-15% click rate. Think that low clickage number is pretty standard across news sites, and well, sites in general.
Anyhow the part that's interesting with facebook is that there is no homepage on facebook. Everything's fairly temporal, so you only have a brief period of time to capture interest. On top of that, it's a hit/miss possibility that you'll start a chain reaction of interest, so I'm amazed when there's a 5:1 or 10:1 or 20:1 ratio of shares to pageviews. It means that facebook as a content platform is totally plausible, which I don't like.