There have been some tantalizing glimpses of the ambition of LibreOffice to provide an Office365-like system for people to host on their own servers - particularly muktware.com is coming soon. However, I don’t know of a single place I can follow what work is being done on this.
It strikes me as being a fantastic addition to LibreOffice, and with real-time collaboration for authorised users I’d drop both Google Drive and Microsoft’s SkyDrive in an instant, but I can’t find anything more up-to-date than last year.