yes college football uses a combination of polls computers to rank the teams each week. The top two teams in the final rankings of the regular season, go to the national championship game. In a year when you have 5 undefeated teams(such as this year), 3 are left out in the cold.
You can click here http://www.bcsfootball.org/bcsfb/eligibility and scroll down to BCS standings for an in depth explanation as to how it works.