Okay I talked a while ago about selling SOA just being about selling, its not magic and all that.
Well I'd like to add another element to the approach...
Understand what the hell you are trying to sell first. Don't start with a vague idea about what the business wants (they probably know) and then talk in vague terms about SOA as being important.
Understand the problem, link SOA directly to the problem and most importantly don't talk about any crap that the business just doesn't care about. So what if you use Web Services, REST, Pink Pixies or a bunch a smack addict monkeys to do it... if you meet their goals then they just won't care. And don't talk about all of the possibilities... just talk about the one that you think they should do.
Be clear, be concise, be definite.