Valve in their weekly update has mentioned that "in the coming weeks" we will know the release date of the continuation of Half Life 2.

As we’ve mentioned before, we’ve been hard at work on the continuation of Half-Life 2 for some time now. Soon, as part of the upcoming Half-Life 2: Episode One, you’ll find out about what happened to the Citadel after the end of HL2, what happened to your nemesis Breen, and how Alyx managed to survive the explosion at the game’s end. You’ll also learn a lot more about Alyx, since nearly the entire episode is spent with her at your side.

During the development of Half-Life 2, we at Valve were frustrated at how long it took us (six years!) to ship the game. With that in mind , the decision was made to try an episodic approach to the next Half-Life products, each designed to reveal new story, gameplay, and the latest Source technology in four to six hour experiences.

Over the coming weeks, we’ll keep you informed about the game’s status. For now, head over to Computer and Video Games site to read an interview with Valve’s Robin Walker about Episode One.

From Steam Powered. (link to the interview at Computer and Video Games is broken, we have fixed it in the text above).