The website, http://www.nltk.org, says mid 2011 in a very vague manner. I would like to start using NLTK however I have done a fair amount of work with Python 3.x and I don
For those who got here wondering when will nltk support python3:
Good news, the NLTK 3.0 series (currently on alpha and in development since Jan 2013) now support Python 2.6, 2.7 and Python 3 (http://www.nltk.org/nltk3-alpha/), We'll probably see a stable release soon :)
And the book is also being updated for python3, available at: http://www.nltk.org/book3/