There were NO zombies in 28 Days/Weeks later. They were Rage victims, they did not die. In fact you see Rage victims dying of starvation and exposure.
I have no preference for walkers or runners, but i really hope they dont screw up World War Z. I love that book so much and am disappointented the film has deviated from the novel so much.
Having said that the trailer does look very good. Fingers crossed.