Just visited a part of rainforest (March 2013). As the site consist of several reserves, National Parks or ecological stations and mostly due to bad weather I decided to stick to one location to have an overall view of the area.
Because of communication issues I go to Peruibe (4 hours by bus from Sao Paulo - Terminal Rodoviário de Jabaquara, there are several buses daily) as the starting place for Jureia-Itatins Ecological Station, in fact a huge reserve, located just close to Peruibe town. If you cross the river you are already in the Jureia Park. The most beautiful place and highly recommended is called Cachoeira do Paraíso and is located some 25 km from Peruibe (there are some buses daily to get there at least in theory, because due to weather conditions the bus may occasionally not operate - it is better to check on Peruibe bus station a day before) or you can walk - on the asphalt road it is possible to hitch-hike.
It is written everywhere that there are only certain amount of people entitled to go to Cachoeira do Paraíso (small lake and waterfall, photo) but I did not encounter any troubles to go there - it is also not necessary to have licensed guide to go there as the path is well marked.
Some practicalities: I stayed overnight in Peruibe. There are a lot of accommodation places as this is huge touristic resort (Atlantic Ocean). Bus terminal (Terminal Rodoviário de Peruíbe) is located in the southern part of the town. From bus station there are occasional local buses to Jureia-Itatins Ecological Station (Nucleo Itungucu or Barra do Una). Good asphalt road is from Peruibe to Guarau hamlet, afterwards there are only unpaved local roads.