One company that continues to baffle me with their non-presence in SaaS is SAP. Nearly two years ago Matt Asay and I sat shocked on a CSFB panel just after Shai Agassi proclaimed that SAP had spent over $1 billion on BBD before it even got out the door.
Over on the Enterprise Anti-matter blog Josh Greenbaum finally finds out why SAP BBD is so late and potentially DOA--a fundamental design flaw in the system, along with what seems to be a misunderstanding of building large-scale applications.
The main issue regarding the delay of BBD has to do with operationalizing the on-demand model in a cost-effective way. This translates to a realization that the existing release of BBD, now in use by some 150 customers, can't be scaled up to handle thousands of customers in a cost-effective manner. This is a major operational problem to be sure: SAP can ill afford to ramp up to a massive deployment of BBD if it's not cost-effective to do so. Klaey mentioned that these operational issues seem to have been dealt with in the next release, which is slated to come on line in the "next few months."