The idea is to have a portlet that can be shown in the dashboard displaying an option to upload an attachment, but this is a project attachment, so it is displayed in the dashboard. If the user has rights to administer the project, the upload attachment is present, otherwise only the list of attachments (file name and description) is shown.
One might think this functionality overlaps with confluence, but I don't think so, this is a minor functionality that in my case would be use, for instance to post release binaries and installation docs, so users and IT people from my customers (I'm a system integrator) can download the latest versions.