Using the recent (1.5) version of pip, I get an error when attempting to update several packages. For example, sudo pip install -U pytz results in
First, you should never run 'sudo pip'.
If possible you should use your system package manager because it uses GPG signatures to ensure you're not running malicious code.
Otherwise, try upgrading setuptools:
easy_install -U setuptools
Alternatively, try:
pip install --user
This is of course for "global" packages. You should ideally be using virtualenvs.