I believe this behaviour is strange:

>>> import pymongo
>>> conn = pymongo.Connection()
>>> conn.foo.bar.find
<bound method Collection.find of Collection(Database(Connection('localhost', 27017), u'foo'), u'bar')>
>>> conn.foo.bar.findOne
Collection(Database(Connection('localhost', 27017), u'foo'), u'bar.findOne')
>>> conn.foo.bar.findOne()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib/python2.6/dist-packages/pymongo/collection.py", line 774, in _call_
self.__name.split(".")[-1])
TypeError: 'Collection' object is not callable. If you meant to call the 'findOne' method on a 'Collection' object it is failing because no such method exists.

Why is the findOne function not callable?