It looks like Sony may be getting ready to roll out two new e-readers, one of which might replace the existing PRS-700 model. The rumor started when a poster at the SonyInsider forums discovered a pair of tech manuals for two new Sony Reader devices, the PRS-300 and the PRS-600 (links are to the service manuals in Google docs). Sonyinsider suggests that the PRS-600 will replace the PRS-700 based on the latter no longer being available at the SonyStyle store.
The service manuals tell us that the PRS-300 will have a 5" non-touchscreen display, 440 MB of available storage space and looks to be pretty-barebones; presumably an e-reader for folks on a tight budget. The PRS-600 has a 6" touchscreen display, 380 MB of on-board available storage, SD/MS slots and an audiojack. There's no indication of any sort of wireless capability for either unit.
It's interesting that this rumor crops up just a few days after Sony & Google announced that Sony Reader owners can now access over a million public domain e-books via Sony's Google e-book store. These books are optimized to work on the newer Sony Readers (PRS-500 owners are out of luck) and presumably on any future Sony e-readers.
All this news comes just a week after Barnes & Noble announced their partnership with Plastic Logic, which will eventually give readers access to half a million public domain books on the Plastic Logic e-reader.
I guess it's a good time to be a fan of the classics.