Getting into natural language processing has never been easier these days thanks to the popular natural language toolkit (nltk). Python, nltk and even the book that teaches you nlp are free! Although nltk was designed by its creators with pedagogical considerations, Jacob Perkins (@japerk) showed with his nltk demos that it can serve as a serious API. His blog http://streamhacker.com has become a standard source of tips and hacks for nltk users, and his "Python Text Procesing with NLTK 2.0 Cookbook" is the natural choice for everyone who wants to be a pro nlp guy.