Maybe I'm wrong but I think Samuel Wanjiru will be to the marathon what I thought Kenenisa Bekele would be to track several years ago. I do know that marathon is another beast compared to the 1/2 marathon; therefore, my prediction is based on my belief in Samuel Wanjiru talent. I believe the guy will show the world that his endurance in the marathon is what Kenenisa's is in the 10000m.
Samuel Wanjiru in my book is a marathoner waiting to happen. He may not go undefeated like Kenenisa in the 10000m but the marathon world record will eventually follow the name of Samuel Wanjiru. In the next few years I think he could improve 10-15 seconds in the 10000m and anywhere from 20-35 seconds in the 1/2 marathon. If he stays healthy and focused I think his endurance and body's enegry proficency will be better suited for the marathon then his great 1/2 marathon performances.