Project Lively

Project Lively is an Office App that combine the best of both worlds between traditional files and online storage. Project Lively enables perfectly normal, everyday Office documents to be treated as such in every way — store them where you like, email them to whomever you like, post them online wherever you like, and work with them offline. But like magic, whenever you’re working on any copy of the document, it always has the latest content, from anyone who edited it.

Read more about the project and get FAQ at http://aka.ms/projectlively