I've given up caring.

Valve pissed off a lot of people with their funked up attempt at HL2's episodic releases. Then they ditched on Ep.3 and decided to roll it into HL3. The final straw was to clam up about it completely. All they had to do was say don't hold your breath, this is going to take years.

If and when they do release it, I'll probably jump straight in like a lemming of course.

I only ever played a rubbish port of HL2 demo on the PS3 - never played L4D either. Neither especially interest me.