I don't know much about these things and don't bother too much with the news, just waiting for the game itself but I remember I had seen something about GPS tracking using GT5 and a Lexus IS-F on the main GT Planet page. Now I just saw this posted on Autoblog. Check it out:
http://www.autoblog.com/2010/02/26/real-time-wrc-video-gaming-just-around-the-corner/
http://www.autoblog.com/2010/02/26/real-time-wrc-video-gaming-just-around-the-corner/