While the SOA model is accepted for BI in the area ETL, there more areas that it can pertain to including reporting, dashboards, performance management that have a much greater inpact.
Every application needs one of the above areas of BI interfaces in addition to its own ETL or data input interfaces. We have been focusing on implementing the whole BI interface as a reusable framework at reportlaunch.com.
I presented this topic at the SAPPHIRE conference on how Service Oriented Business Intelligence (SOBI) creates a huge ROI when the same functionality is not build over and over again throughout an enterprises various web applications. Not to mention that it would provide consistent information utilizing MDM, DW and ETL in applications that dont normally get access to those technologies.
Last, but not least by leveraging, the whole BI stack in your SOBI architecture you actually leverage the investment you have already made in not just ETL but in your enterprise BI tools.
By reusing training, installations, server configurations, etc a common enterprise BI platform can provide a large percent of the structured ,read only information content needed throughout an organization.