With a flurry of commotion, Valve released five new gameplay trailers in the past two days. Because the trailers were just made public, there are no Google video made available for them yet. However, you can count on me to post them here once they do become available.
You can check out the trailers
if you have a Steam account.
Here is an Episode Two trailer (YouTube)
released earlier in the week to whet your appetite. Episode Two, along with Portal and Team Fortress 2 , are scheduled to come out in the first quarter of 2007 (sorry, no Christmas treat this year).