The Pac 10 is a tough conference this year, but the teams at the top of the standings have only themselves to blame for not having higher national rankings. Each year, the teams in the Pac 10 play relatively (compared to the SEC) tough non-conference schedules. This year while USC, Cal and UCLA did well in their non-conference play, the four teams at the top of the league standings all stubbed their toes in non-conference play.
The Ducks and Beavers lost to Boise State and Cincinnati. Arizona and Stanford lost to Iowa and Wake Forest. Imagine what the national rankings would look like right now, if the Pac 10 had won those four games. The Ducks would be ahead of Boise State. The Beavers, Stanford and Arizona would all be ranked more highly. Everyone's strength of schedule in the BCS system would be that much higher.
One of the keys to USC's long-time high rankings has been their consistent success in non-conference games. For other teams in the Pac 10 to be considered in the race for the national championship, they need to play and win games against significant non-conference opponents. Boise State, Cincinnati and Iowa have turned out to be significant non-conference opponents, but you have to win those games.
For the Pac 10 to win a second BCS bowl bid, collectively they need to win a higher percentage of the non-conference games. This year, if the Pac 10 had won those four games, we would be talking about the likelihood of two BCS bowl bids for the Pac 10. To become national champions it is very competitive, but for members of the Pac 10 other than USC they will have to pick up the slack in non-conference games to be considered.