Great news. Twapper Keeper, the Twitter archiving platform, has gone open source. A version that can be installed on your own server is now available via their Google Project page. A hosted version is also available.
As well as being free and open source, you can also access Twapper Kepper APIs and export data in a variety of formats.You can find out more at both the blog and community site. There’s also a demo to play with. It would be great to see how this works with a Twitter analysis tool like ThinkUp (formerly ThinkTank).