SOAP gives companies more capabilities to link systems both internally and externally across the Internet with other companies. In a marked difference from previous communications protocols, SOAP's XML-based messages transport over the Web regardless of what operating system, object model or language particular applications may use. This allows businesses to easily exchange data with each other over the Internet. SOAP is based on popular standards and is platform and programming language independent. Companies are free to choose platforms that are best suited to solving their problems regardless of the operating system.
Firewalls are no longer a barrier to communicating over the Internet.
Enables heterogeneous interoperability of data, components, business processes and applications over the Internet. Simple and easy to implement. SOAP concentrates on the specific task of executing procedures on a remote computer. I think SOAP is an important piece of the technology to finally create distributed component based applications on the Internet. With the remote procedure call capabilities provided by SOAP people can now create applications talking to each other instead.