While trying to catch up with the Instagram craze I came across a very good masters thesis. “Consumer Production in Social Media Networks : A Case Study of the Instagram iPhone App” by Zachary McCune published in June 2011.
Obviously it is a bit dryer and longer than typical articles on the web. It certainly held my attention for 80 pages. You can read it online.
The dissertation provides some context for understanding social media in general. In the case of Instagram six types of motivation for participating are identified through user interviews : sharing, documentation, seeing, community, creativity and therapy.
That Zachary actually got involved in the community rather than observing from a distance makes for some great insights.