A proposal mentioned back in May, to replace the 250cc GP class with 4 stroke motorcycles has been decided.
The new class will be 600cc 4 strokes with a maximum of 4 cylinders. Replacing the 250s with something else makes sense as everyone moves away from 2 strokes but it will be interesting to see if the 600cc class will be a technology leading segment like the 800cc MotoGP machines are.
The new rules begin in 2011.