Data warehouses and the business intelligence applications built atop them are typically highly customized, making software as a service (SaaS) a less common form of deployment for data warehousing systems. Still, as pointed out in this Internet Evolution article, it doesn't mean that software as a service wont apply.
"In contrast, data warehouses and the business intelligence applications built atop them are typically carefully crafted and highly customized, even though the underlying software may be fundamentally similar across enterprises. Companies that manage to create a working data warehouse frequently hold their business analytics close to the vest.
"There's also a limit to what can be done in a pure Web-based model for business intelligence. While there are Web-based analytical packages already available for vertical applications, like Web analytics, the complexities of even the simplest business process analysis dwarf the sorts of things software like Omniture and Google (Nasdaq: GOOG) Analytics do."