Ran across this today - I've been hearing about Google coming out with internet "hard drives", but haven't seen it yet (not counting this interesting bit-o-software I found while searching around). This is the Microsoft offering and it sounds pretty good - here's the quote on what it is. You can read the full description here.
FolderShareTM allows you to create a private peer-to-peer network that will help you to synchronize files across multiple devices and access or share files with colleagues and friends. You no longer need to send large files via email, burn them to CDs/DVDs and mail them, or upload them to a website. FolderShare allows you to share and sync important information instantly with anyone you invite, making it the perfect solution for personal or small business use.