Dahlia:

I do not think it is a one-or-the-other choice.    Basically, BPM is done to logically partition the organization, and then this partitioning is used as an input to come up with a SOA.

Tony

Business process management (BPM) - Model, automate, execute, control, measure and optimize the flow of business activities.

Service-oriented architecture (SOA) - An architectural approach for constructing software-intensive systems from a set of universally interconnected and interdependent services. 

With Cloud computing, SOA is even more popular, as Cloud computing is another example of a Service-Oriented Architecture.