How does mashups fits in a SOA strategy? I can see that some BPMS have similar capabilities for UI development. I see greater value at a "Composite Application" approach. Is this correct?

Mashups and SOA compliment each other very well.  In short, mashups deliver SOA out of the ‘basement’ and into the hands of business-focused consumers.  We’ve written a bit about this in the past:

http://blogs.jackbe.com/2007/08/implementing-soa-without-mashups-you.html.