We're starting the last day of The Internet Turning 40 with the session that I'm in as well - but the first speaker is José van Dijck, who introduces the idea of 'interpretive flexibility' - an approach for examining technologies that remain in flux. Why and how do technologies become dominant over time; how can we trace this process while it is happening; and why is it important to do so? She is applying this specifically to Twitter (and microblogging in general) here.
There are four factors here: technologies and services, mediated social practices, cultural form and content, and business models. All of these are important when examining emerging platforms, of course. Microblogging, José says, is both a tool and a service - and its versatility is crucial to its success. When it was launched, it was unclear what it would become; by 2007, it was adopted and integrated by a large number of other social media platform, and in the process adapted its interface and technological specificities to their needs (but this took place the other way around, too). Since then, there has been an 'appliancisation' of Twitter, turning it into a closed, applied platform, and reducing its versatility and openness.