Will Avatar 3D be out on DVD?

No, there is a 2d DVD, with special features including unseen scenes on Earth as well as other extras

It will be released on 3d blu-ray this November

Edit: the studio has commented that 3D is not currently in the pipeline

http://gizmodo.com/5475243/avatar-coming-to-3d-blu+ray-this-november-updated-or-not