According to (Google translated) Virgula:
It seems that the dream of the Brazilian fans of the saga Twilight will come true. Tuesday, July 13, the director and president of RioFilme, Sergio Sa Leitao commented on Twitter that part of Dawn can be filmed in Rio de Janeiro.
Sergio posted exactly how, at about 10am, "The RioFilme, SEC and River Film Commission are working on that part of the fourth film in the Twilight saga to be filmed in Rio."
Brazilian Twi-hards best start lining up now for a peak at Isle Esme :)