Half...

But the Big 10, PAC 10, SEC, ACC, Big 12, etc. signed a contract at the beginning of the BCS to recognize the winner of the BCS NC as the United States college football National Champion.

But, the NCAA doesn't even recognize anyone as a champion, actually. There are many different polls that crown certain teams as number one and as National Champs, but the only two polls that matter are the AP/Coaches poll.