I think a synagoge was attacked in Brazil or Argentina killing a lot of people. IIRC Iran is blamed for it.
It was in Argentina, in 1996.
About the attack in Brazil, hitting the statue of Jesus the Redeemer would only kill tourists, but it would make possible the attack to be videotaped too.
I can see no obvious reason why would they attack us. The only small possibility I can think is something related to Brazilian troops helping the Australians in Eastern Timor. And, in the extreme case of they really do it, I just can't imagine the Brazilian government sending troops abroad to fight terrorists, the most extreme thing that could happen is, if the attack is really related with something happened in Timor, Brazil would send more men there. Also, it could lead to some individual actions against mosques and Muslims in the country, but nothing more than it.