It may look like a dual GPU graphics card with an all enclosing heatsink, but in reality it is a full terabyte of SSD storage that you plug into a PCIe slot. Hidden within the enclosure is four 256GB MLC-based OCZ SSDs in RAID 0 and 256MB of ECC DDR2 RAM doing duty as the local cache.  The  ‘Z Drive’ will just be their introductory model, they will soon finish their terabyte SSDs, and will be creating the same type of product, only with 4TB of storage and likely a bit more RAM.  Seeing as how this drive is going to retail between $1500 and $2000, you can expect the 4TB model to be fairly dear.

You can read more about it at Engadget.
OCZ's huge RAID - Storage  1