Ghostcrawler's hoping this answer "gets read," so we'll help. A player asks why Blizzard is worrying about armor penetration with the Scourge Strike ability -- isn't, they ask, ArPen getting removed in Cataclysm like we heard at BlizzCon? The answer is basically no: Armor Penetration rating is getting removed from gear (along with Block value, Defense, Attack Power, and a number of other gear stats), but Armor Penetration as a stat is not getting removed from the game. Talents and other abilties will still depend on removing and penetrating armor, even if your gear selection won't revolve around it. They'll still be balancing it, but as players choosing gear, it won't be a part of our calculations there.
Make sense? Just because you don't see, say, Attack Power on gear doesn't mean you won't have an Attack Power number governing how much damage you do. It just means that the AP you have will come from stats like Agility and Strength (depending on your class and a number of other factors) rather than gear adding directly to AP. Of course, as Ghostcrawler says, these changes aren't even coming until patch "4.0" and the Cataclysm expansion, so there's still lots of gear choices and balancing to do before then.