American Airlines is partnering again with TAM that is set to join the Oneworld alliance in 2014. TAM is still a member of competing Star Alliance.
American Airlines and TAM are starting to codeshare each others flights between the United States and Brazil. TAM will add its code for many domestic AA flights and AA will do the same for Tam flights within the Brazil.
TAM used to be a partner with American Airlines previously, but this was canceled once the airline became Star Alliance member.
I remember using some American Airlines miles for TAM flights within Brazil and we should again be able to do this in sometime 2014. This codeshare agreement doesn’t include reciprocal frequent flier benefits, but those will come with the Oneworld membership.