The landscape of services in the enterprise has changed significantly for both service providers and service clients over the last few years. In the IT services domain, the mega IT outsourcing service deals with a sole provider are diminishing fast. A typical service client is now consuming multiple IT services, from specialized providers, and services contracts has become smaller in size and duration. More importantly the line of business, not the IT, owns the decisions and the relationship for consuming services. This has also shifted the service consumption input from IT requirements into the business requirements. This new world is posing a new and unique set of opportunities and challenges for service providers in offering services, which include third party providers, to their clients, and for service clients to consume services from multiple providers. To facilitate offering and consuming such multi-vendor services, in this paper, we present a conceptual architecture for an open services platform which enables a given server provider (a service integrator) to offer services to its clients that are a mixture of its own and other services from third party providers. It also enables service clients to look for and choose services from multiple vendors in a seamless, integrated and consistent manner.