compact flash boot? [thinkpad x31, but also others]

my thinkpad x31 has a compact flash slot, which is basically a short
pcmcia slot in this case---almost every notebook likely has one, so my
question is fairly portable. many desktop computers have compact
flash card slots, too, though often usb based. the compact flash
memory itself is also having good speed, with some vendors advertising
10MB/sec. (266x speeds---I don't believe it, but presumably it means
reasonable fast.)

I am now thinking about installing ubuntu on a 2GB fast flash drive.
I guess booting a computer from CF usually doesn't work, so I may need
to install grub on the IDE hard disk, perhaps create a small boot
partition on the hard disk, too; and after bootup, umount the /boot/
partition, and try to convince the hard drive to spin down. (can
standard internal 2.5" IDE drives spin down on command?) a compact
flash system should keep the system cooler and save battery. if I get
lucky, it may even be a little faster (due to faster random access
times, not streaming speed, of course). if I need huge storage, I
can always spin up the hard drive, remount my partition, and then spin
down the driveagain.

has anyone tried this before?