American Airlines made an announcement two weeks ago that the airline would start codesharing with TAM on August 22, 2013. You can read my piece about it here. These two airlines used to be partners before TAM decided to join the Star Alliance.
American didn’t announce that earning miles on TAM coded flights would become again possible on the same date, but apparently it did. You can access AA’s web page for TAM flights here.
You can now earn award miles (not elite qualifying) on TAM operated and coded flights. You can earn elite qualifying miles per AA’s own chart IF you are on American Airlines marketed (on AA codeshare) TAM flight. Redeeming miles on TAM is not yet possible.
I was trying to find any information about earning TAM miles on AA flights, but TAM’s website is such a mess.
Earning elite qualifying miles and points on TAM flights will become possible when the airline joins the Oneworld Alliance. This is expected to happen sometime in the second quarter of 2014, although nothing has been announced for sure yet. Redeeming AAdvantage miles for TAM flights may become possible before that.