It looks like the
Rockbox open-source MP3 player firmware is starting to get noticed. After a few years of hobbyist hackers independently shoehorning it into running on various players, often in spite of the manufacturers, one player manufacturer, SanDisk, is reported to be
negotiating officially porting it to their hardware and supporting it. Which could be very good news, especially if they contribute their port back to the project, ensuring that it can keep up to date with developments.
Unfortunately, being the product of a flash memory manufacturer, the SanDisk players are all flash-based, and peak at 6Gb (though do have SD-card slots, so you can add an extra gigabyte or so if needed). Now if someone made a 40-60Gb hard-disk-based player that ran Rockbox by design, I'd be interested.