My Head hurts with SOA

I don’t know why but SOA gives me a headache.
What is it and what is new about it.?
It seems to be a number of things. Maybe it includes API's, maybe some middleware, maybe the API's are based on web services, maybe the infrastructure has some Quality of Service (QOS) for delivery, XML is surely involved. It certainly seems to indicate that it connects applications and provides standards but are these ones we already have and are we just embracing them under a new name. Is it the new EDI standard that was once based on things like ‘EDIFACT’ but for internal and external application integration?
I have done a little bit of research and don’t think I am the only one confused? If I say to a vendor are you SOA compliant he will probably say yes. Because he has XML/API/Web services or whatever else he can use to back up his statement.
I am a practical guy working at the coal face so I need a practical explanation that I can relate to the real world and not some ‘consultancy-speak’.
Anybody out there who is not confused and can explain it in practical terms?
Should I worry about it?