On October 1, 2009, Michael Bay revealed that Transformers 3 had already gone into pre-production, and its planned release is July 1, 2011.
The writers Orci and Kurtzman are reportedly not returning to the third movie.
Shia LeBouf and Megan Fox are supposedly both confirmed to reprise their respective roles.
In a hidden extra for the Blu-ray version of Revenge of the Fallen, Bay is speaking about Transformers 3 and his plans and desires. During the video you catch a glimpse of Unicron . . accident . . . coinsidence?
Also, Ray Park is supposedly confirmed to a 'major role' in Transformers 3.