IGN: "Are you waiting for Half-life: Episode 3? Or maybe you're thinking Valve's ditched the episodic format altogether (and you'd probably be right). Regardless, don't hold your breath for a sign of life from Gordon Freeman any time soon. We know it's not going to be at E3 2011, and there are two big reasons why Valve would continue to hold off showing the world what its been working on.
One, gameplay is king. Two, there's just no need to rush it."