Computer Graphics World has a nice article about Half-Life 2 and some of the technology behind it. Its interesting they used XSI and plan to ship a light version with the game (its actually a nice program - its nice to see some attention brought its way).
You can read the article here:
[color=blue]http://cgw.pennnet.com/Articles/Article_Display.cfm?Section=Articles&Subsection=Display&ARTICLE_ID=200690[/color]
Im really looking forward to the game, if not just for the modding possibilities. People are sure to have a field day with it! (I know I would if I had the time).