I agree with the speculation but you can't ignore the fact that the majority feel it was a definite penalty. For a club like Blackburn though who are fighting for our survival these decisions are a lot bigger for us. United have arguable already won the title and given the problems currently plaguing the other 3 of the big 4 i'd wager now that they will take it. A point against United or even a win would have been fantastic for us but for me the ref has botched 2 major decisions, he's not sent Ronaldo off for kicking out (who has then gone on to score the winner) and he has not awarded a penalty for a foul on Pedersen.
As for the tripping, Rafael makes contact. Due to that factor the referee has only two options to choose from, penalty or dive. If Pedersen trips it is due to Rafaels intervention.