Co-owned folders coming to OneDrive!
Basically you can share a folder with someone which then behaves like one of their own folders, meaning they can add\edit files and sync it to their own PC.
I've personally been waiting on this one for a while so I can organize documents and photos that other family members can access
It's going to be interesting to see the limitations of the implementation. You can do something similar with DropBox, but the shared folder size counts toward each users storage quota (presumably to prevent someone creating a bunch of accounts and sharing the free storage with themselves)