Interesting stuff. I've never thought of booting from CardBus. I usually don't leave a card in when I power down (too many machines, too few peripherals), and if I need to boot from a PC Card, it's always a standard PCMCIA-compliant device (CF adapter, Type III hard drive).

Toshiba made a 5GB Type II hard drive, but I don't know whether it's CardBus or PCMCIA. They seem to be in the $100 range still, so I haven't bought one yet.