Sheevaplug Booting From SD Card (Best instruction and it works)

The steps are:

1. Find out what name your system calls the raw SD card device
2. Format and partition the SD card
3. Create a filesystem on the SD card
4. Mount the new card
5. Copy over the OS from the NAND Flash
6. Change the uBoot settings to boot from the SD card
7. Save some wear&tear on the SD card

http://www.randomexploits.com/projects/sheevaplug/sd-boot.htm <--- Detail steps