Valve's New Game Announced, Detailed: Dota 2
Adam Biessener from gameinformer can confirm that:
"The rumors and speculation can cease. Valve is making Dota 2, we've played it, and it's already amazing even though it's not coming out until next year. And we haven't yet laid eyes on Dota 2's biggest innovation: a radical approach to integrating the game's community back into the gameplay itself."