All of the people who complain and whine about wanting it to be a DLC, you're loving handicapped.
Valve can do what they want to do. HL2:Ep3 will come when it comes, get over it.
And, personally, Half Life isn't as great as everyone says it is. It's just a generic FPS with some nice storyline.
I, for one, am going to buy L4D2 because I loved the first L4D, and I'd like to see what they put into the second.