Half-Life 2 Steam Preloads

Half-Life 2 Fallout (thanks GameSpot) has more news from their forums as Gabe Newell made a post yesterday indicating that today is the day Half-Life 2 assets will begin pre-loading for some customers over Steam:
HL/2 pre-load will begin tomorrow. It was ready yesterday, but we decided to use the bandwidth to get out the VST first since I get pelted with zillions of questions from people asking how their PC will run Half-Life 2.