Toward cloud-agnostic middlewares

Cloud computing is a natural progression of service-oriented architecture. The Web as the platform: data with Web 2.0, programming and development with mashups, and deployments and resource provisioning with cloud computing. However, the Web was not necessarily designed to be an on-demand compute platform and infrastructure and certainly not designed to be a network for data centers which is what it is displacing with cloud computing. What are the challenges to advance cloud computing? For example, how do users of compute clouds make efficient usage of the heterogeneous nature of the Web and specifically of the choices between potentially engaging with public clouds versus creating enterprise private clouds, or some hybrid combination thereof? Additionally, since there are usually no single answers, due to a variety of compute workload demands, how should cloud providers and cloud users harvest, create, and utilize best practices in this new platform, thereby encouraging improvements in cloud engagements?