Markets and marketplaces are ancient human artifacts, but in recent years they have become ever more important. In part this is because marketplaces are becoming computerized. Together with the introduction of smart phones, this also makes them ubiquitous. We can order car rides to the airport, plane rides to London, and hotel rooms for when we arrive, all on our smartphones. And as we do so we leave a data trail that is easily combined with other streams of data. This is changing not only how we interact with markets, but also how we manage and regard privacy. I'll discuss some recent developments in computerized markets and speculate about some still to come.

I'll give an overview of the growth of kidney exchange and of the computational, economic, and behavioral issues that arise. Kidney exchange has grown into an enterprise involving many hospitals and overlapping exchange networks, and in the process the set of strategic players has changed, and so has the patient pool. I'll discuss how the market design has evolved to keep pace with these changes, and further challenges that remain, for the medical community, for economists, and for computer scientists.

As multi-hospital kidney exchange clearinghouses have grown, the set of players has grown from patients and surgeons to include hospitals. Hospitals have the option of enrolling only their hard-to-match patient-donor pairs, while conducting easily arranged exchanges internally. This behavior has already started to be observed.