Thanks to the post from Graham Attwell and successive mention by Nancy Rubin I came across the dissertation by Clint Lalond titled, The Twitter experience: The role of Twitter in the formation and maintenance of personal learning networks that at first glance (see the abstract below), is another article in support appears to provide insights into the support of Twitter in professional development.
Abstract
This qualitative phenomenological study involving in-depth interviews with seven educators in K-12 and higher education examines the role that the microblogging service Twitter plays in the formation and development of Personal Learning Networks (PLN) among educators. A double hermeneutic data analysis shows that Twitter plays a role in the formation and development of PLNs by allowing educators to; engage in consistent and sustained dialogue with their PLN, access the collective knowledge of their PLN, amplify and promote more complex thoughts and ideas to a large audience, and expand their PLN using features unique to Twitter. This research also examines the nature of a PLN and shows that participants believe their PLN extends beyond their Twitter network to encompass both face-to-face and other ICT mediated relationships. Secondary research questions examine how Twitter differs from other social networking tools in mediating relationships within a PLN, what motivates an educator to develop a PLN, how trust is established in a PLN, what the expectations of reciprocity are within a PLN, and what is the nature of informal learning within a PLN.
In my summer course that I just finished teaching, EDT 6060 – Trends and Future of Technology in Education, I tried for the very first time incorporating a required Twitter chat exercise into the weekly activities. My goal in doing so was to expand the discussion beyond the scope of the typical Blackboard discussion space and to encourage my students to begin engaging in conversations with others within the field. Since we were looking at current events within the field of educational technology, this was the perfect course to incorporate such an activity on Twitter given the plethora of resources and fantastic ongoing conversations that take place on Twitter. 
