The Library of Congress announced that it has acquired and will archive every public tweet since Twitter’s service started in 2006. That’s more than 50 million tweets per day. Twitter declared, “[it is] very exciting that tweets are becoming part of history.”

Notable tweets include:
Obama’s tweet when he won the 2008 election: http://tiny.cc/srs68 and the first tweet from Twitter co-founder Jack Dorsey: http://tiny.cc/aa2nt.

The Twitter archive joins the Library’s Web capture project that already has stored 167 terabytes of digital material.

There are some limitations. Personal tweets will not be collected and the Twitter archive will be available only for scholarly and research purposes.

Google doesn’t think you should have to wait for the Library of Congress to make archival tweets available—it’s turning on a feature that lets you choose a date and “replay” the tweets from that point on. Google’s search combines Twitter updates with those from MySpace, Facebook and Buzz.