The info is incorrect. Its been confirmed by a blue (and by the fact its completely obvious) that rewards are calculated when you turn the quest in, NOT when you accept it (therefore you will get XP for completed quests turned in after you upgraded to WotLK, not money).

Case in point, when you ding 70 and still have 4 quests completed, you turn those 4 quests in and now get lots of gold for them instead of no XP and only a tiny amount of gold.