Libjpeg is required for getting jpeg support on Mac in Python Imaging Library. To get it and install, do
$ curl -O http://www.ijg.org/files/jpegsrc.v8c.tar.gz $ tar zxvf jpegsrc.v8c.tar.gz $ cd jpeg-8c/ $ ./configure $ make $ sudo make install
Note: You may have to create /usr/local/include
$ port install jpeg