September 30th is the release date but,
Official Transformers Movie Website has been updated with the Transformers: Dark of the Moon Home Release Info.
At the moment you can only see the update on a mobile device (see image).
The release is happening on September 30th, 2011 (as previously rumored to happen) which is only 29 days away.
The third movie is available on Blu-ray, DVD and Digital Download.
Update: Our good friend Liselotte found out that, at the blu-ray.com forums, a member claiming to be working on the Home Release mentions that a 3D Edition will be available this December. But of course, do take it with a grain of salt.
Update 2: Nelson; the admin of Official Michael Bay website mentions that the 2-Disc Special Edition won't be out till December. He also confirms the 6-Disc Trilogy Edition arriving in a metal Autobot logo casing.
Looks like I'll be holding out until December for the version with the special features. Bogus.