According to a snippet from Developmag, the award honours "the person who has contributed to the growth of the games industry, not limited to developers". In other words Metal Gear Solid 4: Guns Of The Patriots was really, really bloody good. Old Snake took the award for best character too, highlighting Metal Gear Solid love.
Monster Hunter Portable 2nd G on PSP earned the title Best Seller Grand Prize. And it really was the best seller too. That game hasn't been out of Japans top-ten in an age.