the wensite joystiq had a intervieuw whit Polyphony Digital (Kazunori Yamauchi). he said that proloog is what theyre working whit and enhancing. as you probably know 01/08 will be a new and big update.. and the man said whe don't need to expect gt5 before 2010 also gt4 on psp will be released after gt5. i hope theyre wrong. found it on
www.gunk.be