Alfresco Share is a team- and project-based collaboration client that sits on top of the Alfresco repository. The goal of this project is to provide a microblogging component that can run within Alfresco Share and any other web application built with Alfresco Surf.
This component installs easily as an Alfresco AMP for the repository tier and a ZIP for the Share/Surf tier. See the introduction for more details.
Note that as of 3.4 Community, Alfresco added their own status component to the Share user interface. It's not as cool as this one but you may want to take a look before you decide which one to use.