The goal is to archive readable URLs in the tweet archive by replacing all URLs from shortening services. You can run it with twitter-archiver -f ThomasAJung to follow all links or twitter-archiver -r bit.ly,t.co,goo.gl ThomasAJung to follow the links of selected hosts.
The archived output changes from:
228771182638419968 2012-07-27 10:37:54 CEST
to:
228771182638419968 2012-07-27 10:37:54 CEST
You can read the Shortcomings section of the Wikipedia article about URL shortening if you are interested why you should replace the shortened URLs.