I read a great interview with US Mountain Running Team member Eric Blake (“Quadzilla”)  on www.craftsbury.com.  Eric was the US Mountain Running Champion in 2006 and 2008, and was a member of the Bronze medal winning US Mountain Running Team at the 2008 World Mountain Running Trophy in Switzerland this past September.  
“CRC: Mountain running courses. Can you tell us a bit about what the quintessential course is? It seems to encompass a real variety – up and down, longer/shorter, cross-country conditions to brutal paved ascents like Mt. Washington. Are there limits to the course design/layout that organizers must follow, or is the sky the limit?

Eric Blake: Most courses fall into two categories “up and down” or “uphill only.” Most races are between 10 -12k. Some are on trails but I prefer races like Mt Washington: on-road and uphill only.
There are restrictions on the course lay out such as high altitude, too much pavement and/or stairs. The course in Switzerland was tricky. Some very steep parts mixed with other parts that were not too bad. It included muddy trails, roads, and even some stairs.”
To read the complete interview click here.