The Journal of Broadcasting and Electronic Media (vol. 56, issue 3, 2012) has released a special open access issue that focuses on social mediated publicness. The issue is guest edited by danah boyd and Nancy Baym of Microsoft Research. The editor of JOBEM is Zizi Papacharissi, one of Culture Digitally’s participants.
Here is the link to the note from the editor.
You can find the table of contents and links to the articles here.