Most of what I've read suggests that the basic building blocks are massed produced and different manufacturers have different approaches to then taking those bits and sticking them together. Some companies then make a point of saying how they don't do it like that (I want to say 'Trek' at this point, but I'm really not sure). There was a UK lot in the current Cyclist talking about how their frame is completely manufactured in the UK, might be the Moda one linked higher up, I'd need to be at home to check for sure though. As with everything like this, I'd expect to find the more mass produced (and therefore cheap) something is, the fewer people there are doing the initial producing, just because of economy of scale.