The Library of Congress is the national library for the United States of America. It holds some of the largest collections of written, published, media, and other forms of recorded history. Wednesday the Library of Congress announced that they will also be storing all Twitter Tweets that are published online. So your tweet about that awesome cheeseburger will now be saved with the Library of Congress.
For those whom are concerned about privacy, only public Twitter feeds will be included in this national archive of tweets. The goal is to record some of the most important tweets that are shown on twitter, much like how President Obama announced his victory on Twitter in the 2008 Presidential Election.
Source: http://www.cnn.com/2010/TECH/04/14/library.congress.twitter/index.html