When trying to start the built-in WSGI server in Pyramid after starting a new project, pserve refused to do anything useful with my project. Turns out I had forgot to run setup.py in my projects virtual environment to set up all the dependencies:
From my projects folder:
../bin/python setup.py develop
.. of course, you’ll remember this if you read the README.txt that the pyramid setup creates for you in your project directory.