I've written a simple post at my personal blog (Yes, I have one, but it talks more about my daily life, personal projects and geek stuff) Mobideia about the use of a hidden class 'Scanner' from the module re, responsible for handling with regular expressions.
The practical example includes a simple Tweet Extractor for identify the URLs, (http://www.aimotion.blogspot.com), usernames (@joao), hashtags (#django), Retweets (RT) and words. It may be very useful for you who wants to play with Natural Language Processing (NLP) and text mining on Twitter.
In order to avoid the replication of all text here, I've decided to place the links for accessing the post:
English Version (by Google Translate):
I hope you enjoy!