Fairfax County Public School System offers two student mediation conferences each year.  The attached document specifies the conference specifically geared toward High School students. 

About the conference from the site:  "Throughout the course of the day, these peer mediators will be able to discuss their program with other peer mediators and generate ideas for improving it. Time is also allotted for these students to attend workshops of their choice that aim to improve and develop more advanced mediation skills."

The conference is scheduled to take place on November 19, 2010 at George Mason University.  See the attached notice for more information.

Additionally, you can find information here: http://www.fcps.edu/dss/ips/ssaw/ConflictResolution/Conferences.htm