From http://en.wikipedia.org/wiki/Service-oriented_architecture: A system based on a SOA will package functionality as a suite of http://en.wikipedia.org/wiki/Interoperability http://en.wikipedia.org/wiki/Service_(systems_architecture) that can be used within multiple, separate systems from several business domains.
Meaning: You don't offer an applilcation, but you offer a set of services (for example WCF or a web service). Now these services can be consumed by application (these can be web-based or not)
From wikipedia: For example, several disparate departments within a company may develop and deploy SOA services in different implementation languages; their respective http://en.wikipedia.org/wiki/Client_(computing) will benefit from a well understood, well defined interface to access them. http://en.wikipedia.org/wiki/XML is commonly used for interfacing with SOA services, though this is not required.
I think, with a service oriented application, that you refer to an application which consumes these services.