The Twitter Authentication provider was created by Oliver Hine, utilizes source code provided by Shannon Whitley and was created after I read the blog post by Joe Brinkman detailing additional authentication providers.
Installation is like any standard extension for DNN 5.x, in DNN 4.x you will need to goto the Host > Advanced > Authentication > Install page. It will allow another method for your users to authenticate securely to your website. After the installation process you will need an oAuth Twitter Application Key and configure the callback url to point to your dnn login url. In addition you'll need to provide the key / secret api keys to the authentication provider in your Admin > Extensions > Twitter Settings control.
I also added an additional setting for the initial release. When the Auto Follow mode is enabled the provider will create a friendship / following connection between the App Username you provided and the user that is authenticating on your website.
Please feel free to follow me @oliverhine on twitter, or contact me with any questions or suggestions.
Any donation would be greatly appreciated and will go directly to the development of free extensions for the DotNetNuke community.