If not you get errors such as
AttributeError: 'FileDescriptor' object has no attribute 'message_types_by_name'
wget https://protobuf.googlecode.com/files/protobuf-2.4.1.tar.gz
tar -xzvf protobuf-2.4.1.tar.gz
cd protobuf-2.4.1
./configure;make;make install
cd python
python setup.py install