Another one in the bag.
The first year I did this was in 2007 - may have been the first year that it was a Save Mount Diablo event instead of whatever the previous charity group was.
So I missed 2 years of volunteering since then, and my involvement looks like this:
2011 - not
2012 - not
In 2007 I called to volunteer and the organizer went over some possibilites and when she found out I had a pickup truck suggested that I be a backpack driver. I'd only had my truck for a few months at that point so it was perfect timing. Lots of nice advantages to having a truck, this is one of the best.