http://www.ebeijing.gov.cn/html/EV.htm:

People, who want to volunteer for the Olympic Games 2008 can find information and apply on the website above.

For everyone who is interested in doing volunteering job during Olympics. I just found out that applicants may submit their applications from to March 2008 and they will mainly be recruited in Beijing area. There should be 70,000 Games-time volunteers for the Olympic Games and about 30,000 Games-time volunteers for the Paralympic Games. More than 450,000 applicants have already registered. The first trainings just started, so don't hesitate if you really want to do this!!