Hi,
it's a difference whether the BIOS supports USB CD/DVD drives or not.
If there is support for booting USB CD/DVD drives in the BIOS, the BIOS emulates it as a normal CD/DVD drive. So from boot managers point of view it is like booting from a normal CD/DVD and there is no problem.
But if there is no support in the BIOS, the USB driver of the boot manager needs to do that emulation itself. This isn't currently implemented. But if you look at the
status page you will find the following:
Sat 07/Nov/2009
Today, I played around with the USB CDROM driver. Mostly it works and then it stopped working. I dont know why and how fast I can fix it.
So maybe in future releases there will be support for USB CD/DVD drives even if the BIOS doesn't support it.
Regards
bront