This may turn out to be a pretty useful feature for super active Twitter users. An option to download your entire tweet archive is slowly being rolled out across all profiles starting today.
I don't see it on mine yet, but I see people tweeting about how impressed they are with how easy it is to access and how little space it takes to download thousands upon thousands of tweets posted as far back as Twitter's first year.
You can look for the archive download option by going to "Settings" and scrolling all the way down the page in the "Account" tab. You should eventually see a "Request your archive" button.
If you don't see it, give it some time. In the meantime, check out Twitter's official announcement on its blog and some screenshots for what you can expect once it pops up on your profile.
Photo: Screenshot of Twitter.com