Editorially is a newly-launched plain-text service that allows users to collaboratively write and edit documents. Editorially auto-saves your work and keeps track of multiple versions of a document, so writers and editors can easily see and compare how the piece has evolved. Users can invite friends and colleagues to provide conversational feedback on a document, and Editorially provides a simple activity log that shows what everyone is working on. Prospective users can sign up at the Editorially website.
video via Editorially