Just a note:
The U-Boot image is slightly broken in this version of the PSP. The command for programming the OneNAND is broken, I rebuilt the image and same problem. I'm not going to bother delving into it just now, but suffice to say, if you follow the instructions in the Getting Started Guide and you use the current U-Boot image, you won't be able to reflash anything with Samsung memory.
Also, I should note that the Getting Started Guide has since omitted some important fixes that need to be made to the re-flash scripts, but the scripts themselves in the package have not been updated, so you need to refer back to some older documentation on how to do this.
Good luck...