Transformers: Revenge Of The Fallen's cowriter, Roberto "patience of a saint" Orci, has been fielding fan questions for months over at the TFW2005 forums. He finally broke down and admitted that Megatron is coming back.
Yes, all the toy spoilers were right. Megatron is in the new movie, despite all the claims to the contrary. But he still hasn't addressed the crucial "Dinobots in Transformers 3" question, because he wants all the Dinobot-lovers to keep suffering. Megatron concept art from Josh Nizzi, via Film School Rejects. [TFW2005, via Transformers Movie Chronicles]