When Gran Turismo 5 released at long last, developer Polyphony Digital still wasn't quite done with it, and spent the time since working on tweaks and updates. Now various retailers are listing an "XL Edition" for $39.99, and smart money is on this new version packing the updates in from the start.
Amazon, Newegg, and Buy (via Joystiq) have all listed the unannounced product, with no word on what the "XL Edition" actually is. It seems likely that this will be our own version of Japan's Spec II disc, which packages the game with its spec 2.0 and all previous updates. Sporting "improved physics and AI," a number of new vehicles, and significant tweaks, the current Gran Turismo 5 is arguably a different game from the one that released over a year ago.
Then again, the listings could be something else entirely, or nothing at all. We've contacted Sony for official details, and we'll update as more information becomes available.