http://depts.washington.edu/ccce/digitalMedia/newsimpact.html
http://www.dailysource.org/about/impact
http://www.allacademic.com/meta/p_mla_apa_research_citation/0/9/0/9/1/p90915_index.html

A few links you may find useful. Try searching for impact of the internet on news, rather than simply online news.