IN THE WAKE OF this past summer’s Grand Tour, and the debates surrounding the Venice Biennale and Documenta 12 in particular, some of us were left wondering what, if anything, could restore confidence in the idea that biennials remain a relevant and vital form of exhibition-making. One possible answer: the Sixth Mercosul Bienal in Porto Alegre, Brazil. Organized by Gabriel Pérez-Barreiro (soon to leave his post as curator of Latin American art at the Blanton Museum of Art, in Austin, Texas, to become director of the New York– and Caracas-based Coleción Patricia Phelps de Cisneros), the Mercosul