Microsoft has developed and released via its CodePlex site an alpha version of a new open-source content-management system, codenamed "Oxite." Microsoft made the Oxite source code available for download on December 5. Oxite is available under the Microsoft Public License (MS-Pl), one of its OSI-certified open-source licenses.
Oxite is an open source, standards compliant, and highly extensible content management platform that can run anything from blogs to big web sites. We know this because it runs MIX Online.
Oxite provides you with a strong foundation you can build upon - pingbacks, trackbacks, anonymous or authenticated commenting (with optional moderation), gravatar support, RSS feeds at any page level, support for MetaWebLog API (think Windows Live Writer integration made easy), web admin panel, support for Open Search format allowing users to search your site using their browser’s search box, and more
You can get a pretty good idea of how it works from this video: