Where is Episode 3?

Well I just finished Half Life 2: Episode 2 and I find myself really excited at the prospect of a third and hopefully final episode. The game was full of action, story telling, and amazing character development. The final act ended in one hell of a cliff hanger and it is impossible for me to imagine not having a third installment. At this point however, it would definately make sense to just name the next entry Half Life 3. If you play episode 2 and see where the game is taking them, then you will understand what I mean. I have been keeping my ears peeled for info from Valve about a follow up but I haven't heard anything at all! How could this be?! I must say that it would be a pity for Valve to make just another 4-5 hour episode considering how long we must wait for it so hopefully the next installment (if it is in fact, in the works) will be a full game that ranges from 10 - 12 hours like the original Half Life 2. I can't wait to see what Valve has in store for us next.

-Nick