Intelligent Enterprise's Doug Henschen put together a list of the top five myths of SOA, based on the comments of industry executives. My own comments added. My view: let's bury these myths, then bury the shovel.
Myth #1 - "SOA is easy." A statement of the blindingly obvious, but it needs to be said, since too many vendors are touting SOAs-in-a-Box. However, it may be accurate to say, in many cases, that "SOA is easier." Easier than what? Easier than attempting to manage or change business processes hard-wired into siloed proprietary systems.
Myth #2 - "Once top executives are sold on SOA, your troubles are over." See Myth #1. You gotta work it, work it, and keep on working it. Henschen's article says that "sticking to SOA approaches and standards requires ongoing discipline, strong governance and support from rank-and-file IT and business managers as well as top executives." Amen. Work it, work it, and keep on working it.
Myth #3 - "You can simply wrap legacy systems with services." See Myth #1. Actually, I could spend all day on this one, because SOA does enable legacy systems to be surfaced as standard-grade services. I think the mythological part of this statement is the adverb "simply."
Myth #4 - "You can buy SOA out of the box." See Myth #1. 'nuff said.
Myth #5 - "If you're using Web services (such as SOAP over HTTP), you've achieved SOA." See Myth #1. It's a little too easy to build Web services. You could build 10 of them in an afternoon. But, then you end up with a JBOWS architecture (Just a Bunch of Web Services), which will grow into a different sort of SOA -- a Spaghetti-Oriented Architecture. SOA requires orchestration between the services and governance.