We're happy to announce we've just released a new "Edit with app" feature, which lets you edit files stored in Confluence using your desktop apps. Open MS Office and other files types with the default app on your computer, edit them, then automatically re-upload your changes as a new file version.
Take a look at this blog post for all the details.
Looking for similar functionality for Confluence Server? Check out KontextWork's awesome GoEdit add-on on the Atlassian Marketplace.