Cloud computing is today’s rage and tomorrow's threat - proprietary clouds have the potential to become a worse lock-in platform than the proprietary world of yesterday. In this talk we examine how you can put together a pure open source cloud for SOA and enjoy the benefits of service-oriented cloud computing without the risks. Cloud computing is primarily about three things: on-demand scaling for peak load management, multi-tenant sharing, and parallel execution. On-demand scaling refers to the ability of the cloud to allow an application to consume more resources as the demand on the application increases and for this to happen without over participation from the developer. Multi-tenancy relates to how a single application can be shared and used securely (and independently) by different consumers. Finally, parallel execution enables an application to request additional hardware and to execute in the entire set of nodes as a parallel computer. The most challenging part of the puzzle is providing a single rogramming model for application developers. Proprietary clouds such as Amazon EC2, Google AppEngine and Microsoft Azure do offer many of these capabilities. However, signing up to a proprietary cloud is like checking into the proverbial Hotel California: “You can check out but you can never leave!” During this presentation we will look at how a collection of open source components can be combined to form an open source cloud that addresses all aspects of cloud computing but that also leverages open standards to establish a model whereby applications running on open source clouds can fully interoperate with other cloud platforms as well.