Update #1: Paramount Pictures has apparently set June 29th 2009 as the official release date for Transformers 2, according to BoxOfficeMojo.

The [1] Los Angeles Times is reporting that Steven Spielberg and Michael Bay have signed with DreamWorks to make Transformers 2, which will hit theaters in Summer 2009. However, Michael Bay [2] wrote last week on his blog that he might be “jump ship” to make a pre-strike movie. If Bay gets involved in a big budget picture like Disney’s Prince of Persia, who knows when Bay would be available for a Transformers sequel.

It took a little longer than 12 months to make the first film (pre-production to completion), and that probably involved a longer pre-production process (due to initial concepts and designs). So for Transformers 2 to hit screens in July of 2009, the film would need to begin production by Fall 2008. And if Bay were to make a pre-strike movie, that is the date he would need to be free by.

Update #2: [3] Will Michael Bay direct 2012: The War for the Souls Next Before Transformers 2?