Western Digital MyBook Thunderbolt Duo..
They will come in either 4TB (2x 2TB) or 6TB (3x 2TB) with speeds around 600 MB/sec read and write it will be an awesome addition to your system at home in , because who wants to carry around something so big?? they should now made that into a usb stick or something of the similar siize with the same capacity!!
For more pictures and info on it check it out at Source: