This paper seeks to frame one aspect of the Smart Grid discussion which has been under-recognized in regulatory and policy debates. Significant discussion has focused Smart Grid attention on the technologies and on technical interoperability, there has been little if any attention to questions of the structure or the operation of the market(s) in which the technologies will function. The authors contend that the market structure required for a successful Smart Grid is best understood by a "platform" framework. We present our view of the interrelationship between that market platform, ultimate customers and power suppliers. It is our conclusion that without a thorough vetting of the market structure within which Smart Grid technologies will function, the full value of the innovations cannot be realized.