As reported on comingsoon.net....

"The "2008 ShoWest Edition" of the Dolby newsletter (in PDF format) has a list of upcoming 3-D releases and includes Transformers 2 (as well as Steven Spielberg's Tintin). We're hearing that, although it's on the list, the sequel is not a lock yet for a 3-D release. A final decision will be made based on the availability of Digital 3-D and IMAX 3-D screens. The big problem facing the Transformers sequel is that Ice Age: Dawn of the Dinosaurs comes out just five days later and would rule out a majority of the Digital 3-D screens."