As reported by Darryl Taft in eWeek (Microsoft Releases CodePlex with 30 Projects), we launched CodePlex 1.0 today. As you may recall, CodePlex uses Team Foundation Server for version control and work item tracking. It adds forums and RSS feeds to create a collaborative software development portal for a growing list of shared source projects.
Redmond, Wash.-based Microsoft announced CodePlex 1.0 at the Open Source Business Conference in London on June 27, highlighting the development portal as a means of sharing source code.
UPDATE: As Michael Ruminer notes in the comments to this post, there's also an article on CRN (Microsoft Invites More Projects Into Shared-Source CodePlex), which includes quotes from Michael and his experience creating the TFS Source Code Version Tree Browser project (see also: CodePlex Project for a Version Control Tree Browser).