This article compares current and future interface concepts and the dramatic cost implications of interfaces. With the increased importance of exchanging information between enterprise solutions, a coordinated interface architecture should be considered. An interface architecture for the extended enterprise requires a shared communication language, one that standards greatly facilitate. While traditional interface approaches, such as point-to-point and hub and spoke, have been widely deployed in the past, they are costly to maintain and do not provide loose-coupling and fast return-on-investment. Web services and the Enterprise Service Bus (ESB) are promising interface technologies that provide access to loosely-coupled services using commercial standards and existing infrastructure to support a service oriented architecture. Numerous cost drivers, such as the interface architecture and functional, technical, and organizational characteristics significantly impact the cost of an interface. An understanding of interface technology and cost drivers will ensure system architects are better equipped to design and deploy cost-effective interface architecture.