Nor vs Nand
From eLinux.org
There is a good introduction on the differences between NOR and NAND flash at:
http://www.commsdesign.com/design_corner/OEG20031022S0011
Samsung seems to be able to boot off of NAND flash.
The abstract for this paper is interesting: http://csdl.computer.org/comp/proceedings/iccd/2003/2025/00/20250474abs.htm (can't get to the paper, but I'll try through some other avenues)