Here's Another Better Quality Trailer

Lots of these to sift through on YouTube, but this one is the best I've seen.

http://www.youtube.com/watch?v=OlNyocBG6tI


Edit: The authenticity of the above YouTube video is questionable (thanks WILLQUICK). But that's okay, since a non-bootleg version is now available here: http://www.empireonline.com/news/story.asp?NID=21492.

Edit 2: Trailer also available at Cloverfield Clues.