Motor (which is indeed my non-blocking driver for MongoDB and Tornado) had a 0.1 release to PyPI yesterday. It had an odd history prior, so there are various versions of the code that you, dear reader, may have installed on your system. All you need to do is:

$ pip uninstall pymongo motor
$ pip install motor

Motor will pull in the official PyMongo, plus Tornado and Greenlet, as dependencies. You should now have Motor 0.1 and PyMongo 2.4.2:

>>> import pymongo
>>> pymongo.version
'2.4.2'
>>> import motor
>>> motor.version
'0.1'

(The lore is: I started Motor last year in a branch of my fork of PyMongo, so you could've installed an experimental version of both PyMongo and Motor from there. Then we transferred Motor into its own repo within the MongoDB.org organization on January 15. And on February 1st a zealous fan actually grabbed the "Motor" package name on PyPI and uploaded my code to it, then transferred ownership to me, just to make sure I could use the name Motor.)