There is a conversation that I've had close on a hundred times now in the past 8 years about how to sell SOA to the business it goes like this
Business: Why do I want to do SOA? Isn't it just another IT acronym
Me: Do you understand how your current IT estate works?
M: Would you like it to look like the business?
M: Then that is what SOA is about, its about making the IT estate look like the business, evolve like the business and be costed in line with the business value it creates
Then you show them what the Business Service architecture piece is and how you will create a heatmap for them of where IT adds value and where you should be moving towards Utility (OpEx) spend and now you have a business person bought in and a goal on what the IT estate and its supporting organisation should look like.
Its not rocket science and it has nothing to do with technology.