After managing 53 years without any changes, MotoGP (the preimer road race class) gets its third proposed engine capcity change in a decade.
In 2012 it has been decided that the main class will now be opened up to 1000cc machines. The bore will be restricted to 81mm, the number of cylinders to four.
Other details will be ironed out in the meantime, with some suggestions that a production based engine and free rein on chassis design, as per the new moto2 class, as a possibility.
MotoGP web link