Suzy Cox is a lecturer in educational technology and educational psychology at Utah Valley State College and also a doctoral candidate at Brigham Young University (working with Dr. Charles Graham). She is currently working on her dissertation which seeks to develop a conceptual analysis of the TPACK framework.
She maintains a blog (mytpckdissertation.blogspot.com) that tracks her progress in this task. Suzy has conducted a thorough literature survey of pretty much all that has been written about TPACK and has done a good job of laying out the myriad definitions and explanations that have been given for each of the overlapping components of TPACK. Her work in progress can be found here.
I see work like this as being critical to the development of the TPACK framework (and its future applicability for research and practice), mainly because it points to contradictions and ambiguities in how these terms have been used in the past. (I must admit looking over her document I could find multiple examples where Matt Koehler and I have been guilty of sloppy writing/thinking.) It is, however, only by the kind of systematic work that Suzy has done that the field can develop better and more robust definitions. I look forward to seeing how her work develops over time. As a clock on her website indicates she her defense is in a couple of months. Wish her luck.