In his keynote Larry Ellison nicely explains SOA in the context of Fusion Applications. His point is that customers do not want to replace exisiting apps, but integrate with them. He even used the word BPEL ;-). He made a very interresting point: A packaged application is no longer closed, but through usage of SOA middleware at its core opens itself up to integrate internally with other custom or third party applications.
Larry as well showed a nice slide on the BPM architecture with processes orchestrating services. He used this to show that Fusion Application is not only customizable through integrating with other applications via SOA services but as well through changes at the business process layer.
My main conclusion is that with Fusion Apps a packaged application is a white box where they used to be black boxes. This can open up tremendous opportunities for integrators when they offer creating a custom application based on Fusion Application using BPEL, ADF, SCA etc. creating the UIs, workflows and processes the customer needs integrating with existing systems he has in place.