There seems to be a lot of discussion these days regarding the relationship between DDD (Domain Driven Design) and SOA (Service Oriented Architecture).
Udi Dahan says they are orthogonal, and via that post, Richard Campbell says they are opposites.
My answer is that they are unrelated.
DDD relates to the implementation of a Service. How a Service is implemented within a SOA is unimportant, and the adoption of DDD is just an implementation detail. The Service may be implemented in any manner - as a procedural script, functional program or as object-oriented code - in Logo, Perl, RPG or C# - who cares?
That being said, one thing I advocate is that a Service is not equivalent to an Application. A single Application may be distributed, and itself consist of a number of Services that communicate through messaging across AppDomain or process boundaries. Perhaps that is where most confusion lies.