CloudPlug, CTERA's flagship product, generated some buzz at CES in no small part because of its innovative packaging. CloudPlug crams the brains of NAS into a white box about the size of a wall-wort transformer or PowerLine network adapter. A Gigabit Ethernet port connects it to your network and a USB 2.0 port provides the connection to user supplied external hard drives.
As one would expect for a low-end NAS, CTERA's devices are Linux based, have a Web management interface and support access via CIFS and FTP. Support for snapshots and building RAID sets out of external USB drives (hopefully just RAID 1 -- the thought of a RAID 5 set over a single USB channel makes my skin crawl) is a step up from the standard feature set for SOHO NAS.
One advantage of the USB storage is if the CloudPlug fails you can just plug the drive (formatted NTFS) into a local PC to access the data.
But built-in online backup is what really makes the CloudPlug, and CTERA's C200 two-bay appliance, special. CTERA devices can back up their data, including multiple version support, to a CTERA portal server running in a central data center somewhere on the Net. Data is of course AES encrypted before it's sent across the Net and CTERA uses compression and block-level data de-duplication to minimize network traffic.