Not enough yet. I think that social media will prove helpful, but their sue so far is far too limited. However, much good (as well as bad) information can be found on the web. See www.Jpc-se.Org to learn about developing policy issues. (i am the chair of that international committee.).
Yes. Yes, this is a good use of social media. There continues to be investigation into how best to advance public health using social media, but so far people have looked into using twitter to help identify disease outbreaks, the use of blogs in combating pain, and the use of social media as it affects suicide.