sony will soon replace the PRS-500 reader with an updated model, the PRS-505 (this probably was the main reason for the desperate ads in july/august). but as it turns out, the most radical change of the device seems to be the color: silver rather than black. other than that, it has undergone only very minor overhauls (at least no more duplicated navigation buttons), and it sports the exact same mindset of building a device that is as limited as possible.
well, there is one other notable improvement: the PRS-505 uses the newer generation of e-ink's electronic ink display, which means a whiter background, higher contrast, and 8 gray levels instead of 4 (i complained about the older-generation display when i bought the PRS-500 back in june). the better display means better anti-aliasing, which should improve the legibility quite a bit. it would be interesting to compare the two models side-by-side and see the difference between the display generations.