Gran Turismo Kart Racing?  Well yes.  Announced at GamesCon, Gran Turismo will include karts for racing, and no there are no blue shells to throw.  Originally the karts were going to be included in a later version of the series, but because info about them was leaked the team decide to included them in Gran Turismo 5.  Below is video from Kotaku of the kart racing. 

Sony had quite a few announcement regarding Gran Turismo 5.  Polyphony Digital has included a Course Maker tool.  While not as detailed as you would think, the Course Make only lets you input a set of parameters and it builds the course, you can then go in and edit details of sections.  These courses can be shared with friends and and raced online.

Also introduced it the B-Spec mode of the game. In B-Spec you don't drive the cars, you manage the drivers.  You an monitor their physical and mental states and give them strategies during a race.  Push them to far though and they will start ignoring you.

 Lastly is the 3D Photo Mode.  With this you can take 3D photos of your cars, of course though you will need a 3D capable TV and the glasses to take advantage of it.