It's currently available at Amazon.com for pre-order.
Transformers: Dark of the Moon (Two-Disc Blu-ray/DVD Combo + Digital Copy)
50GB Blu-ray Disc
Two-disc set (1 BD, 1 DVD)
Digital copy (on disc)
Reportedly, there are no special features in this version, but come November - a "deluxe" Blu-Ray edition will be released with special features and also in 3D.