pip install does not install the files of the fields directory. The files are now in the tarball (#97 closed) but setup.py does not reference the new fields package.
>>> import mongoalchemy.fields
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named fields
Fixed, and I tested it this time!
0.13.3 is the new version. should be in pypi now.