Jersey,
I have no inside information but my theory is that they operate like a currency market maker. They just move the line according to the action they get without regard to other books' lines. They get so much action it would be wise for other books to key off them and not the other way around. Some books do this and they are the smart ones IMO.
I think at any given time the Pinnacle line represents the dollar weighted consensus opinion of all sports bettors whereas other lines represent the opinion of Las Vegas Sports Consultants for the most part, or their own linesman in a few cases.
Trouble is you don't know whether sharps or squares are pushing the number at Pinny because the squares are so plentiful and the sharps have the big bucks, making their dollar representations in the market roughly equal.
As a generalisation, though, I would say that on nationally televised games, the Pinny number represents the squares' opinion mainly and on other games the sharps'.
Could be totally off base here, but this is what I see from where I sit (which is VERY far away from the action -- may be better to ask an insider).