We've attended a number of events there, including the monthly Thursday night drifting event, where anyone with a helmet and a vehicle that can pass tech can enjoy all the powersliding mayhem they want in a controlled environment. We've only gone to observe, but have found the group to be a well organized, safety conscious band of enthusiasts.
A couple who moved into a house down the road in 2005 (and promptly built a motocross track on their property, by the way), formed a two-person organization called "Community for a Better Altamont", the goal of which is to reduce the impact of traffic and noise in the neighborhood. Our friends over at Jalopnik have an excellent commentary post on the matter that outlines the players, the facts and the hypocrisy.
[Source: Jalopnik, Community for a Better Altamont, Tracy Press]