If the ref thought it was a foul, surely Rio had to be sent off. Although it was a complete dive by Adam, maybe Suarez has been giving them lessons, I mean, Adam hasn't been the 1st one to dive today.
Either way, clever by Gerrard, stupid by Giggs.
EDIT: on seeing the replay, it was a foul, Ferdinand should have been off for a second yellow. I think Adam could have stayed on his feet though.