This has been a hotly debated topic over the Interwebz since GW released a main rulebook FAQ recently.
Q: If a transport vehicle is destroyed in the same turn as it moved flat out what happens to any embarked models? (p70)
A: They are removed as casualties.
Now, the argument comes here from the definition of the word "Turn". Does it mean Player Turn or Game Turn?
Game Turn Example:
One side of the coin is, that if for example, my Dark Eldar raider moves flat out, then is destroyed in the Space Marine player's turn by a Lascannon, the Raider - along with the transported Squad inside - are destroyed and removed as casualties.
This is logical in that if it's moving extremely quickly, then nose dives into the ground after being shot down, the speed it's moved at and the impact it would make, would kill off the passengers inside.
Player Turn Example:
My Dark Eldar raider intends to make a last ditch move towards an Objective that is in Difficult Terrain. Moves flat out over as much and lands within scoring distance of the Objective, but must then take a Dangerous Terrain test. The Raider fails the test, is destroyed along with it's passengers and the objective is then lost.
Personally, I think this is just a mess up on GW's part, by simply missing out 1 word, either "Player" or "Game" in regards to what turn all this happens in. A commenter on another blog pointed out this quote to me, and after double checking it in a Rulebook, I agree this is the best explanation:
Page 9 (I think) of the BRB:
GAME TURNS AND PLAYER TURNS
In a complete game turn, both players get a player turn, during which they perform their actions in the appropriate phases – the Movement, Shooting and Assault phases to be precise. Exactly what happens in each phase is described later. Hence one game turn will comprise two player turns. Whenever a rule uses the word “turn”, both in this rule book and in the Codexes, it means “player turn”, otherwise it will clearly state “Game Turn”.
I've underlined the key sentence in that paragraph. As the FAQ simply says "Turn", according to the Rulebook, it means that it only has any effect during the controlling Player Turn.
I'm aware this isn't a be all and end all to the argument, since people will still argue the toss either way.
The rule says "Turn". Not "Game Turn". Therefore, no shooting down my Dark Eldar raiders moving Flat Out, or Ork Trukks, and destroying everything inside of them.
That's how I'll be playing the rule until GW come back with a clarification.