After watching the England/Australia test, I would have to say that it was one of the worst refereeing performances I have ever seen.
Joubert's refereeing of the ruck was inconsistant at best, incompetent at worst. The amount of times he allowed England forwards to fringe around the ruck to slow the ball coming out was astounding, and you could see the Wallabies getting frustrated with this later in the game.
One particular ruck comes to mind - where Joubert penalised Benn Robinson for not releasing the tackled player (from which England kicked a penalty early in the 2nd half). Robinson's arms are clearly seen rising above his shoulders after the tackle before he went for the ball.
His scrum calls, like a few international referees, are too long, and caused the game to finish without a single scrum!
The amount of knock ons he missed from both sides was terrible.
Frankly, he shouldn't even be refereeing senior rugby with a performance like that.
BTW - England were the better team, but Joubert ruined the game.