This year, Slow Food International's Terra Madre and Salone del Gusto will be a unified event open to the public in Turin, Italy on October 25-29, 2012.  You can make your own way there OR apply to be a U.S. delegate. The deadline to apply is April 1.
To join the international community at Terra Madre as a U.S. delegate, check out www.slowfoodusa.org/terramadre and click "Apply to be a U.S. delegate" on the right side column for the application guidelines and link. OR go directly to the application here:
https://secure3.convio.net/sfusa/site/SPageServer?pagename=USDelegate_Application
Best of luck! Email [email protected] with any questions.