Today I went down to WonderCon in Anaheim only for Ridley Scott's Prometheus. I was hoping for some footage or clips to be shown, but all we got was the new trailer in 3D. And that trailer ended up online pretty much immediately. Was the trip worth it? Yeah, because experiencing this thing with booming sound on a giant screen is totally the best way to experience it.
In the meantime you can watch on your computer screen. As for any questions about this being an Alien prequel: Scott more or less confirmed it on stage, and the trailer has this image in it: