I vaguely recalled an announcement by SanDisk earlier this year (Feb. 2009) about their 4-bits per cell flash memory that they call X4 that lets them pack up to 64 gigabits (8GB) on a single die.

CNET reports that products based on this technology is shipping now in 8GB and 16GB SDHC cards and Memory Stick PRO Duo cards.

SanDisk ships 'X4' flash chips

SanDisk, however, appears to be hiding which of their products actually use their X4 technology. A search through SanDisk.com only reveals earlier press releases about the technology but nothing about products using it. Although it probably doesn't matter to the general public, tech geeks like to know about this kind of thing. What's the deal SanDisk?