Ars Technica posted a primer on HDR and a tour of Valve's Lost Coast

I will say this right off the top: I have long been a fan of Valve Software. From the first moment I stepped on the tram in Half Life 1, right through to the final mysterious ending in its sequel, Valve has consistently delivered exciting and fun game play experiences. So when I was given the opportunity to participate in a special technology preview at Valve headquarters of the Half Life 2: The Lost Coast expansion and the new Day of Defeat: Source, I didn't just jump. I leaped.

A primer on HDR and a tour of Valve's Lost Coast