This might not be significant to some, but I am a bit excited to see (or hear) the new voice codec that is supposed to come with HL2. The quality of voice on HL mods was, quite frankly, sub-par; anyone who has used third-party voice chat programs like Teamspeak or Ventrilo will tell you so. I'm interested to hear about this - hearing people more clearly over HL2's multiplayer games would add a lot to the experience.