I'll take "What is not social informatics?" for $200.

Exploring the web, I came across this website. The site is dedicated to hawking the wares of a Marcus P. Zillman and he's co-opted the term 'social informatics' for precisely that purpose.  An obvious reason to exclude Mr. Zillman from your consideration as a commentor on social informatics is that there is not a single bona fide social informatics resource listed on his social informatics resource page.

If you're curious about social informatics research, two better places to start are The Rob Kling Center fo Social Informatics and Wikipedia