Bethesda unveiled the first teaser trailer for DOOM today and while it doesn't show any gameplay footage the teaser does have a few nice throwbacks to the original game (the door sound alone brings back memories of hours spent winding through dark twisting hallways) and the next generation Cyber demon looks pretty awesome as well.
The big reveal for the game is going to happen at Quakecon this year and I imagine that will be the first time we get to see the game in action. Until then you're stuck with this fairly good looking CGI trailer.