AMD Zone has posted some ATI Crossfire vs NVIDIA SLI benchmarks for Valve's newly released Lost Coast level for Half-Life 2.  The Lost Coast level adds support for High Dynamic Range (HDR) lighting:

High dynamic range lighting has been a buzzword in 2005 in the world of PC gaming.  Lighting after all has the power to make computer generated scenes really come to life.  High dynamic range versus low dynamic range brings brighter whites to gaming, and a general more realistic lighting.  So great, more eye candy you say?  Well it can factor into game play, and does with Day of Defeat Source.  Coming from a dark area, and stepping into the light brings about a bit of a glaring, or blinding effect that can temporarily hinder your view.