Quick(!) click on over to ESPN and check out their relatively interesting coverage of ultra running titled "Are these runners ultra-tough ... or ultra-crazy?" I say "relatively interesting" because it's a subject that I've read up on a bit, but, for those who haven't, the article gives an alright overview.

Once you have read it, be sure to check out the "comments section" for a little bonus info and (more importantly) some outsiders takes that end up being somewhat humorous... amongst my favorites are...

"Has anyone suggested a psychiatric evaluation?"
"These guys are just plain nuts."

...and my favorite...

"350 miles in 81 hours is nearly 15 minute miles...that's really not even running. i can chug along doing 10 minute miles for a few hours and i don't consider myself in very good shape."

...as for that last one, let me say this, I truly, 100% believe, (damn near) anyone can complete your standard, 26.2 mile marathon given the time and training. Having said that, 'chugging along' at a 10 min./mile pace for 100 miles is what Scott Jurek did in order to set the course record at Western States, no small accomplishment. Also, dudes' comment above states he could do it for "a few hours," so, going by the rule of 'a few is more than 2' lets just say he means he could do that for 3 hours (and that's probably a stretch), that means he will have run a grand total of 18 miles, still 8.2 miles short of a marathon and (at the bare minimum) 8.3 miles short of a ultra (but seriously, who would put together a 26.3 mile run and call it an ultra? 50K is usually the next step... not always, but usually). I'm not saying 18 miles isn't a good "long run" but really, for a lot of people, what's considered 'hitting the wall' usually occurs somewhere between mile 18 and 22, and for some one who claims to 'not be in very good shape' the final 8.2 miles of a marathon could be disastrous, let alone the final(?) 82 miles of a 100 miler. I probably sound defensive but really, I'm just amused...