From the front page here, and from the Sony press release:
Sony will also provide an update path for owners of the first edition Reader, model PRS-500, so early adopters of the Reader will be able to enjoy this benefit as well.
Since the original reason given for not updating the 500 to ePub was hardware limitations, I'm wondering if this is just another trade-in program, or if they have actually developed a firmware update.
I'm kind of torn on which one I would prefer; $100 off a PRS-300 would be really nice!