Cloud services have become ubiquitous to all major 21st century economic activities. However, cloud services and technologies can be significantly more powerful than they are now. A persistent barrier to further advancement has been the lack of a large-scale and open cloud research platforms. With funding from the National Science Foundation (NSF), the Chameleon project will provide such a large-scale platform to the open research community allowing them explore transformative concepts in deeply programmable cloud services, design, and core technologies. Chameleon will allow users to explore problems ranging from the creation of Software as a Service to kernel support for virtualization. This broad range of supported research includes many other areas such as developing Platforms as a Service, creating new and optimizing existing Infrastructure as a Service components, investigating software-defined networking, and optimizing virtualization technologies. The Chameleon testbed, will be deployed at the University of Chicago and the Texas Advanced Computing Center and will consist of 650 multi-core cloud nodes, 5PB of total disk space, and leverage 100 Gbps connection between the sites. While a large part of the testbed will consist of homogenous hardware to support large-scale experiments, a portion of it will support heterogeneous units allowing experimentation with high-memory, large-disk, low-power, GPU, and co-processor units. The project will also leverage existing FutureGrid hardware at the University of Chicago and the Texas Advanced Computing Center in its first year to provide a transition period for the existing FutureGrid community of experimental users. This will be added to Grid, Distributed and Cloud Computing Resources Subject Tracer™.