Hop Madness 2007 in Salem Oregon is a celebration of all things lupulin, including a tour of a hop farm in active harvest and the Best Darn Hoppy Beer Cometition. The Madness is a 21+ event, ID required. $10 per adult/$15 per couple, $3 parking.
I was planning on heading over for that, but unfortunately I'm going to be out of town that weekend. I think the next brew fest I'll be going to will be the Yakima Fresh Hops Fest (http://www.freshhopalefestival.com/)