Apple has doubled the capacity of the top-of-the-line model in previous updates. You'll remember that the curent iPhone contains either a single 16GB or 32GB Toshiba NAND module. We're not in charge of production at Foxconn, but it seems that six months is enough time to produce a pile of these. This is speculation, of course, but speculation is fun.
Note that Apple uses a pair of NAND packages in the 32GB or 64GB iPod touch. Can you say 128GB iPod touch? We don't know who would need that much storage space, but Apple sells a 160GB hard drive-based iPod, so what do we know? Apple chews up a substantial slice of the worldwide NAND market, so any tweaks to capacity or manufacturing are definitely noteworthy in Cupertino.
Last month the Korean Times accused Apple of manipulating flash memory prices. It's been estimated that Apple consumes 25% of the world's flash memory.