Beginning in March 2007 and going right up until December, Copesul petrochemical company, are sponsoring a series of cultural lectures by leading thinkers of the world. Click here for the homepage, it's in Portuguese but you can get an idea of the dates and people, click on "conferensistas" for the people and "programação completa" for the dates. The lectures are being held at the Federal University or the Catholic University every Tuesday.
A lot of the lecturers are from Britain and the States, there are many others from other countries so I guess the common language will be English except perhaps when the lecturer is Brazilian or from a Spanish speaking country.

Leave a message for me with your e-mail if you require any further info in English.