Still doubting that Sony has a new duo of e-book readers on the horizon? Have a look at this. Sony Insider is reporting that retailer J&R posted up product listings for both the PRS-300 and PRS-600, but both were quickly pulled in order to avoid a stern wrist slap from the suits at Sony. 'Course, neither were pulled quickly enough, and what we're left with is a list of full specifications and MSRPs for the both of 'em. If said sheets are to be believed, the 5-inch (800 x 600 resolution) Sony PRS300-RC Reader Pocket Edition will ship with 512MB of onboard memory, PC and Mac su