Helpful links for Visiting Brazil

Transiting at GRU Sao Paulo airport & customs
Airport transfers in Rio de Janeiro Brazil
Maps of Brazil
Getting between airports in Sao Paulo

Transiting at GRU Sao Paulo airport & customs

Aviões

If you're switching flights at GRU in Sao Paulo, you will NOT need to clear immigration. So if you're flying Sao Paulo-Buenos Aires, you don't need to go through customs in Brazil at all.

This is great if you're short on time. But on the down side, the airport is pretty boring - there are a lot of shops but nothing really exciting, so bring reading material.

There is a United Red Carpet Club too - you might want to consider buying a one day pass at the counter for < USD$50 if you have a few hours to kill. You can go inside, shower, and get free drinks. Not a bad deal.