Age 34, Ashland OR
He's won twice before. Last year, he brought it home with a time of 16:24:55. That is a 9:51 min/mile average. Here is Koerner winning last year's WS 100:
He DNF'd at mile 78 of the 2009 Leadville 100, but came back strong by winning the Miwok 100K in May. He is a grad student at the University of Colorado at Boulder and looks like a wild man when he takes his shirt off to run. There is a documentary out on him called "Indulgence." Here is a picture of his feet after finishing Miwok.
Age 22, Font-Romeu Ermitage, France
He is young, but he has been making quite a splash in the ultrarunning world in Europe. According to Runner's World, he crushed "the field at the 2008 and 2009 Ultra Trail du Mont Blanc, then smashing the speed record on the Tahoe Rim Trail (by 7.5 hours) last September. From December to April of this year, he's competed in the World Cup, the World Championships and the Pierra Menta in ski mountaineering, winning most everything he entered. This spring, he won Spain's Zegama mountain marathon, then ran 800 kilometers across the Pyrennes."
Age 34, Juneau, Alaska
He was named 2009 Ultrarunner of the Year by UltraRunning Magazine. Training in Alaska, he is quite comfortable on snowy trails. He is fortunate: they say the first 20 or 30 miles of this year's WS will be snow-covered.