Gen Con 2012 will feature a playtest area for prototype testing:
 
http://us1.campaign-archive2.com/?u=2f77d2f8c77398c0b064223ba&id=ef381ea5d4#three
 
Application form: http://community.gencon.com/files/folders/pmg/entry324634.aspx
 
Policies: http://community.gencon.com/files/folders/pmg/entry324633.aspx