Blizzard has finally killed off downranking spells in the latest WotLK Beta build. All spells now cost a percentage of base mana. (Not total mana, base mana, which is the mana you have if naked and untalented.) So all ranks of spells cost more or less the same at all levels.
I am estatic about this change. I've been posting about downranking being a problem since 2006. Costs are the single most important part of game balance, and being able to evade costs has always led to degenerate gameplay.
To me, the best thing about WotLK is that Blizzard is finally beginning to take costs, both mana/rage/energy costs and time costs, seriously. This should lead to a stronger, more balanced, and more fun game.