Okay, so much rk26 stuff, I think Ill just throw in some rk27 topic. ;-)
Here is a dump of the rk27xx internal boot rom:
http://alemaxx.al.funpic.de/rk27/rk27xxboot.rom.bz2 (actually its four times the same 8k).
This loads the first few pages of the nand, decrypts it and executes it. These pages normally contain the bootloader that in turn loads the BASE.RKW. Actually I think its quite funny that the ROM loader expects encrypted data. Its kinda soft encryption though. Btw, the firmware on SPMP8000 based players uses 3DES for their proprietary .bin game format (for the 1st k).