Isn't Web Service Orchestration just a new marketing term for the EAI and BPM categories?
Orchestration is closely related to the problems that are traditionally addressed by EAI and BPM. However, orchestration is built on a new service-oriented architectural foundation with the advent of drastically changing the economics of integrating applications and business processes. Orchestration carries the promise of taking integration from the high-end niche and making it available to the mainstream.
Open Standards - Orchestration is built from the ground up using industry standards for XML data interchange (SOAP, WSDL) and for flow choreography (BPEL4WS, WS-Coordination and WS-Transaction). Further, orchestration leverages the full power of a programming language, like Java, for orchestrating services, asynchronous messages and user tasks. Process flow logic can be dynamic, data driven and arbitrarily complex. Through Web services, orchestration provides interoperability with any system that supports these interfaces. For example, both Java and .NET Web services can be orchestrated.
Cost and Scope - Orchestration solutions feature server-based pricing with drastically reduced requirements for specialized consulting services. Orchestration leads itself naturally to smaller-scale standalone projects and to "stepping-stone" projects (start small and build incrementally). Orchestration is the linchpin of service-oriented architecture and the capability to automate long-running, multi-step business transactions which span heterogeneous systems. Orchestration solutions are inherently designed to support distributed business processes.
Skills Availability - Implementing orchestration is applicable for mainstream developers. The learning curve associated with orchestration solutions allows developers to quickly get up to speed on developing orchestration logic leveraging their existing skills (e.g. Java).