Big outcry on the World of Warcraft forums: Blizzard is changing the way spell ranks work, making the mana cost a percentage of base mana, not a fixed number. Thus the mana cost of lower rank spells increases with higher level, and low ranks cost equal or more mana than higher ranks of the spell. That prevents the strategy of downranking, casting lower rank spells on the cheap if you only want a smaller effect. I did that for a while with healing spells for my priest, until the last nerf of that strategy. But now downranking is truely dead.
Personally I'm not that angry about Blizzard removing downranking. But I think the move is not to their advantage, because it shows up a huge flaw of WoW: There aren't all that many different spells. Especially in Wrath of the Lich King, what I saw on the trainers was 90% just higher ranks of existing spells, and only 10% new spells and abilities. If Blizzard can make the mana cost of spells go up automatically with level, then why doesn't the effect go up with level too? The only reason it does not is that then in the second half of the game your trainer wouldn't have anything for you to train in many levels. Removing downranking means visiting a trainer is not a joyous occasion for you to increase your options, but an annoying trip back to the old world with added cost, just to keep your *relative* power constant compared to your level. Where is the fun in that?