No release date has yet been announced, but expect it to be sometime in early November.
Cars 2 will be available in both a deluxe 5-disc combo pack, which includes the film on Blu-ray, Blu-ray 3D, DVD, and digital copy, and a regular 3-disc Blu-ray/DVD pack.
The 2-disc combo pack will be sold in both Blu-ray and DVD packaging, but content will be the same. The release on Blu-ray 3D will be the first for a Pixar film (the Toy Story trilogy won't be far behind).
It seems that Disney will be waiting a while before releasing the film on single-disc DVD—their latest move to spur adoption of the superior Blu-ray format.