WordPress is getting into the intranet(-ish) business, with the pre-release of WordPress P2.
P2 organizes all your files, projects, and conversations on one screen, so your team can collaborate from anywhere. It’s perfect for remote teams, digital nomads, extended families – anyone who doesn’t like email or meetings (i.e., everyone).
I got my P2 installation (if you have a wordpress.com account, you already have one), and it appears to be a simple internal blogging and collaboration tool.
VentureBeat has quite a bit more information in their announcement article: Automattic launches P2, a WordPress-powered collaboration tool for remote teams