Large-scale Internet Data Centers (DC) are empowering the new era of cloud computing, a still evolving paradigm that promises infinite capacity, no upfront commitment and pay-as-you-go service models. Ongoing research towards providing low-cost powerful utility computing facilities includes large-scale (geo)- distributed application programming, innovation in the infrastructure (e.g. energy management, packing), and re-thinking how to interconnect thousands of commodity PCs. In this paper, the authors focus on the latter and review developments that are taken place in architecting Data Center Networks (DCN) to meet the requirements of the cloud. Finally, they speculate on the potential impacts of such utility computing developments in shaping the future Internet by driving incentives of adoption of new protocols and architectural changes.