Commercially, hops are dried at 120-130F. The faster the better as long as they don't get too hot. I get far superior results using a dehydrator set to those temps than drying them more slowly.
Denny, at the event out there earlier in August, I think I remember hearing Perrault Farms mention they were at about 135F and a grower down near Woodburn, OR said they were trying to stay around 130F. It's hard for them to go any lower due to the increased time it takes to get them dried coupled with the additional acreage that has to be dried. Adding drying capacity is a really hefty investment but it'll have to be done if acreage continues to increase like it has recently. http://www.mbaa.com/meetings/archive/2013/proceedings/Pages/44.aspx