Andy Clark's book Supersizing the Mind: Embodiment, Action, and Cognitive Extension is being published by Oxford University Press later this year. Among other things, this book fleshes out and defends the ideas put forward in our joint 1998 article "The Extended Mind". It includes a comprehensive (and I think largely compelling) set of replies to the various objections to the extended mind thesis that have been raised over the last decade, and also has a lot on applications of the extended mind idea within cognitive science.
I've written a foreword to the book, which I've just put online. The foreword will also form the basis for my talk in the Barwise Prize session at the Pacific APA meeting later this week. Of course this short piece doesn't go into remotely the depth of Andy's book, but it gives some elements of my current take on the extended mind thesis, ten years after publication of the original article.