Trailers Weekly: True Grit, Troll Hunter, I Am Number Four, and Skyline Dan Koelsch, October 2, 2010 Trailers Weekly is a feature in which we bring you the most popular and talked about trailers of the week. Sharing trailers is a classic viral practice, and trailers are still the most mainstream way for people to learn about movies. This week we have a several first trailers and…