for an insiders perspective from an academic angle, the award winning the myth of marginality: urban poverty and politics in rio de janeiro, by the american anthropologist janice perlman written in 1976 should be of interest.

the author spent many years conducting participatory research in rio's favelas and in this book presents evidence of favelas' residents as organized, politically active, and civically engaged groups. 

hailed as one of the most important works in urban studies ever written, this book is a must for anyone interested in a better understanding of the dynamics of rio's favelas. this book is also available on google books, and it can be read on this link.   

perlmans's most recent work, titled favela: four generations of living on the edge in rio de janeiro  and published by oxford university press, looks at intergeneraltional develoments and migration in rio's favelas - it has also won several awards and is highly regarded by critics and academics on the subject.