BitTorrent Sync is basically explicitly designed for people who need to move huge amounts of data back and forth between different devices. Now the service is getting support for the network attached storage these types are likely to use.
Cloud-based syncing services like Dropbox, MediaFire and Google Drive are incredibly useful for most most people, but if you have a huge amount of data or need to sync massive files, it's not a very efficient way to move stuff between devices. BitTorrent Sync basically streamlines this by using the BitTorrent protocol to bypass the cloud altogether. A common use might be a video editor that needs to move large files between home and work computers.
Until today though, you've only been able to use the BitTorrent Sync App with mobile devices and your computer. Now, you'll be able to use it with NAS as well, which makes a lot of sense, because you'll probably need some networked storage for backup if you have so much data that the cloud is inconvenient. At launch, NetGear will be the first partner, with support starting immediately, but BitTorrent told us that they will have more partners soon.