This weapon can be used as a heavy thrown weapon with a range of 6/12.
Does the fact that it "can be used as" indicate that it is a heavy thrown weapon for purposes of magical weapons returning to the user?
Citations would be nice.
Based off of @SevenSidedDie's comment on @IainAnderson's answer:
Magic Thrown Weapons return to the thrower after an attack.
If we assume that after some attack with dwarven thrower, that it does not return to the thrower after the attack, then it must not have been a thrown weapon.
Since the dwarven thrower was thrown, then it's can't not be a thrown weapon, and so it returns.
Question 13 of the DnD Insider FAQ: 13. I am using a magical thrown weapon as part of an area of effect power. If I am attacking multiple enemies within that area, do I need multiple weapons, or will one suffice?
One is enough in this case. Magical thrown weapons return to you after each attack, so you’ll be able to use it against each enemy as part of using your power.
Perhaps I don't understand your question, but all magical thrown weapons return to the thrower. I would assume any non-missile-weapon that has a range attached to it would count as a magical thrown weapon.
Yes, because dwarven throwers have existed in previous editions, and there they specifically gain the returning special ability. It's the whole point of their iconic deal.