I was over at the MisticRiver Forums when I came across this
interesting post on the possibility of upgrading the flash in my iFP player.
I did some research, and it seems like it's possible to upgrade, with the 512MiB samsung chips (K9K4G08U0M) as the max chip size you can use. The link in the post above gives a seller of memory chips, so getting a supply is no problem.
I also noticed that he was selling the 1GiB version of this same chip (K9K8G08OUM) - I was hoping that I could use this chip, but the acceptable devices ids list does not have this chip's id (0xd3)
There was also some talk of "piggybacking" a chip on the old one - I think this is possible, just a matter of tying the Chip Enable pin of the new chip to the correct pin on the old chip.
If anyone has some info on how to add an additional device id to the firmware, or have any other ideas, do reply to the thread
Here's the page that inspired all this:
http://www.s1mp3.org/wiki/index.php/How_to_add/change_a_memory_chip