It's not technically a Pac-10 opponent
As for MWC, they added Boise St to make a power play at an automatic bid in the BCS. With or without Utah, they were adding Boise St.
I'm not so sure the MWC adds other teams. Are there any other teams that instantly bring football success? Remember, there are BCS formulas that must be met by the MWC in order to be eligible to be an automatic qualifying conference - adding a weak football team actually hurts them severly in the formulas. Boise St obviously helps.