Out of the blue, Polyphony Digital is releasing a downloadable update for the Japanese version of Gran Turismo 5 Prologue. Once the update is installed replays will not work and some saved data will be affected. This change sounds fairly deep if it’s going to render select information useless and Polyphony Digital has not announced what features the Spec II update adds.
One possibility is Polyphony Digital is giving the “exclusive” content from the North American/European versions to Japan. Not sure about this though! The update might not do anything big. We’ll find out soon either way.
Update: Luke Plunkett from Kotaku explains this update just puts the Japanese release on the same track as the PAL one. Both say "Spec II" on top. Thanks for the info!
Update 2: The "Spec II" update is live and it brings the features announced in the US revision into the Japanese version of Gran Turismo 5: Prologue.