Hi M,
As a foreigner married to a Brazilian, you are eligible (contingent on receiving your permanent visa and being on good terms with the Brazilian Law) to apply for naturalization four years after you´ve received your permanent status.
If you own Real Estate property in Brazil or have a Brazilian child, you can apply as early as one year after receiving your Brazilian "green card". Check the web site of the Policia Federal for more information on naturalization.
This is not a legal advice, just information I was able to come upon on the net and through my research with the PF.
Also search for the Estatuto do Estrangeiro for the actual legislation guiding and controlling naturalization of foreigners in Brazil.
Get a professional legal advice, but make sure that you know the general terms and at least the outline of the law before swimming with the sharks
Regards,
Boris