Forget the third umpire, forget Darrell Hair for a moment, I'm really disappointed in Simon Taufel, ICC's best umpire of the year for having got this decision wrong. As Sambit Bal points out, this is not really the first instance of something like this..
Kolkata 1999 - The victim in that case was Sachin Tendulkar, who had grounded his bat after completing a run, but a collision with Shoaib Akhtar, the bowler, who was moving to collect the throw from Nadeem Khan, lifted his bat off the ground. The throw hit the stumps, Pakistanis appealed and Tendulkar was given out, a decision that led to a mini riot.
Napier 1995 - Dulip Samaraweera, the Sri Lankan opener, attempted a run after tapping the ball in front of him but got back to the crease. Ken Rutherford, the New Zealand captain rifled in a throw and Samaraweera jumped up to avoid being hit. The ball hit the stumps and Samaraweera was declared out by the third umpire.
I do remember the '99 game in Kolkata and that decision did cost India the game. Inzamam's dismissal might not prove that costly. But that is not the point. If the umpires themselves tend to be ignorant of the laws, then wouldn't you love to argue that it is ok for the cricketers to be ignorant too. Should Vaughan be forgiven too if he continues to be ignorant of Law 41?