I haven't even finished Episode 1 yet and already a whole slew of new videos showcasing HL2: Episode 2 are starting to make their way onto the internet.  If you have Steam installed I highly recommend hitting the My Media tab, then click on Browse Media and hunt for the 2 trailers and 5 gameplay videos...your eyes will thank you.  If you don't have Steam installed I'm sure you can find them on the web somewhere, though I haven't taken the time to track them down.  Anyone know the ETA for EP2?