I was just harvesting my first year Cascade hops (got a 5 gallon bucket full!) and was getting ready to dry them in the food dehydrator. I googled up "hops drying temperature and got... THIS: http://www.czhops.cz/tc/pdf/optimisation.pdf An article on optimized hop drying and conditioning.
Very informative, mostly over our heads, but what I got was you want to dry at 62-65C for 2-4 hours and pull the hops when the moisture content is about 10% - when the hop cones reach 61C, according to their charts.
Hope this is useful to some other folks.