Neither listing notes any new features, new instruments or new effects. Perhaps this suggest the same basic program will be released, but could also be a publisher just holding their cards close. The publisher’s listing claims that this new book in the Power series is ideal for the musician moving up from Garageband.
Perhaps we are on the cusp of a new release, but also remember that earlier this year Amazon listed software releases for iWork ’07 and iLife ’07.
Edit: These above book links merely serve as a placeholder for the next edition of Logic Pro Power.