Do suporte MacTeX Lista de discussão :
Howdy,
Try running
pdflatex --version
in Terminal. The first of many lines it returns gives the TeX Live version which is also the MacTeX version. E.g. I get
pdfTeX 3.1415926-2.4-1.40.13 (TeX Live 2012) ...
since I'm using TeX Live 2012 and therefore MacTeX-2012.
Good Luck,
Herb Schulz