A bit of a wordy title, but it's actually an article over on BPM Enterprise written by Jeff Mills, VP of Channel Development and Marketing for Bluespring Software. He discusses the following 10 points in detail, with ROI approximations for each:

1. Eliminating mundane work
2. Sustaining compliance
3. Extending out enterprise applications
4. Simplifying people's jobs
5. Reducing risk
6. Knocking out process-related "pain points" or nits
7. Establishing full visibility into how your business operates
8. Building an agile infrastructure
9. Reducing the burden on IT
10. Building a process infrastructure

Some of these, such as eliminating mundane work, are the low-hanging fruit that may have already been plucked in any process improvement project, but others, such as compliance and risk, will serve to enhance the relatively new compliance procedures that may have been implemented within an organization. The last three are more forward-looking in terms of enhancing the infrastructure, although they don't mention SOA, which would be a key part of any infrastructure rework these days.