The site on the posters was revcom.us, which is the Communist Party of the US website.
http://revcom.us/a/309/stakes-of-the-trayvon-martin-case-and-the-need-to-seize-the-time-en.html
Mexdeaf- Thanks for making it clearer. I mistook an image of Bob Avakian for George Zimmerman- thus my confusion.