I agree with Matt. Cards should not be shown in a tournament. Players should also not state what cards they hold, while playing in a tournament. In a tournament, even if the hand is heads up, each player is still playing against the rest of the field.
Much of what Daniel says in his article below, regarding soft-playing a friend, actually contains arguments against his opinion for showing cards while in a tournament:
http://www.azstarnet.com/sn/printDS/140189