What are the best machine learning libraries for Python ?

I found recently an oDesk job which can match my interest. Client says: “I would like that predictor to be written in Python only, and leverage only publicly-available libraries (mlpy, scipy,scikit etc.)“. Well, it would be good idea to utilize more than one package and check for output F-score, so I googled the most known machine learning packages for Python, there they are:

MLPY and PyML seem to be the most known and mainstream choices. Regarding the list above – Anaconda Python distribution seems to include only scikit-learn package. On the other hand, if your task is connected with NLP only, NLTK package may be enough.

Source: http://www.quora.com/What-are-the-best-open-source-machine-learning-libraries-written-in-Python