FAT, I agree IMHO I can't see the point of the USB version as you need to have modern motherboards to get the USB booting feature but the actual software requirement will run on a P2 200mhz machine, it seems like technology overkill to get around a floppy disc
If you have to put modern motherboards in then surely running a full OS and using the SATA/RAID/Print server functions would be a better alternative
I think the "road map" should've took a right turn at the USB idea and gone straight to either a fully CD config and boot version, or a version running directly off a partition on a hard drive, couple that with PCI IDE support and you could put NASlite on a small 2-4GB hdd on IDE channel 1 and then load up with as many other hdd's as you need. If the boot/config hard drive was accessible across the network but with a little security to stop you accidentally formatting it you could then keep a backup copy of the config/boot files on another pc or even burned to a cd/dvd. Like a back up to your back up machine.
I am sure lots of people think the USB idea is great but to me the biggest plus of NASlite was using up old bits of kit to get cheap NAS, come on guys I bet most of us only paid money for the hard drives maybe a stick of RAM and the software, price these systems up against something like a terrastation!! I reckon you could build a 1700GB NAS box for the price of a 1TB terrastation.