for those willing to improve the portuguese skills. at today's O Estado de S. Paulo, probably the biggest newspaper here, a two-page article on the cortiços. amongst other things, there's the discussion about the rise on the price per square meter on the cortiços. apparently, comparing rents, the price at the cortiços is higher than at formal rich neighborhoods such as Morumbi.
here goes the link, and if anyone is interested i can help (sort of) with the translation.

http://www.estadao.com.br/estadaodehoje/20090412/not_imp353477,0.php