Website 360Monster has reported that THQ and GTR developer, SimBin have parted ways meaning that you're not going to be seeing the Xbox 360 version.
A THQ spokesman is quoted as saying, "THQ and SimBin are no longer working together on the GTR Xbox 360 videogame. Our focus within the racing genre is continuing to build THQ's internally developed Stuntman, Juiced and MX franchises."
We have contacted SimBin this afternoon to see how the creator of Race and, of course, Attack on Pearl Harbor responds and we await comment.