The current pypi version seems to break my django project with what looks like a circular import. I haven't actually looked at where this might be within the piston source, but I am familiar with the type of crash where modules all list as None in the django exception page.
I confirmed this by starting my dev server without piston in the INSTALLED_APPS, which works. Also, when I removed the pip version of piston and directly installed from the repository, the problem was gone.
Might need to push out another update to pypi?