Kernel 3.5 introduces:
This release includes a driver for using an IEEE-1394 connection as a SCSI transport. This enables to expose SCSI devices to other nodes on the Firewire bus, for example hard disk drives. It's a similar functionality to Firewire Target Disk Mode on many Apple computers.
This release also adds a usb-gadget driver that does the same with USB. The driver supports two USB protocols are supported that is BBB or BOT (Bulk Only Transport) and UAS (USB Attached SCSI). BOT is advertised on alternative interface 0 (primary) and UAS is on alternative interface 1. Both protocols can work on USB 2.0 and USB 3.0. UAS utilizes the USB 3.0 feature called streams support.
I have an Arch Linux with kernel 3.5.3-1 and wanna try out this feature.