This is a raw deal for Texas, but the Longhorns are doing a pretty good job of dealing with this situation. While they are sinking into madness in some instances, I think it is understandable to a point. Texas fans need to remember that the only thing they can do at this point is win their bowl game and then complain and hope the AP listens. As I said with Georgia last year, there's no reason to whine now and then lose your bowl game. Doing so will make you look like you didn't belong in the conversation in the first place (such as Michigan in 2006).
While I do think Texas being left out is ridiculous, I do not blame the BCS. It is not the BCS' job nor its intention to determine the participants in conference championships. This decision was the Big 12's, so they created their own problem. Every conference uses BCS rankings at some point for a tie breaker, and I think it's understandable that conferences would use it in some form in order to not leave this thing up to a coin flip (which I believe was next), or some sort of obstacle course game show tournament.
If this situation does result in a split national title, people are going to completely blame the BCS for it. I think such blame would be misplaced. It's not that you could absolve the BCS completely, but I think there are entities you could blame for having a larger role in creating such an instance.
The first to blame should be the Big 12, for reasons I outlined earlier. The next blame should be placed on irrational voters who placed Oklahoma above Texas. How can I blame voters, but not blame the BCS? Simple, the BCS is reactive to the choices the voters make. If voters in both the Harris Poll (which did rank Texas ahead by a small margin), and the Coaches Poll (who defy logic as often as they can), had largely ranked Texas above Oklahoma, the BCS would have appropriately responded.
Again, I'm getting ahead of myself. Everyone lambasting the BCS for having failed this year reminds me that nothing's actually been decided yet