I've just been testing NAND flash on new board using StarterWare. Initially the flash didn't work, but we tracked the problem down to some dubious timing settings in the Startware source code:
#define NAND_WEOFFTIME (31)
#define NAND_OEOFFTIME (31)
These numbers can be found in both examples/evmAM335x/nand/nandReadWrite.c and bootloader/include/armv7a/am335x/bl_platform.h. They are a bit suspicious as CSWROFFTIME and CSRDOFFTIME are also 31. This means CS is de-asserted at the same time as WEn/REn rises, which is the point at which the NAND chip will sample the command.
I'm not sure if these timings were for a specific chip, but better default values are the ones mentioned in the AM335x Techical Reference Manual table 26-11 (NAND Timings Parameters).
Hope this is of use to someone.
Jonathan