You can find it for download at https://manage.autodesk.com/cep/#products-services if you are subscriber.
My personal favorite change is the addition of AutoCAD MEP to the suite. While it includes another way of managing CAD, we do get the benefit of a robust library of architectural elements (doors, windows, etc), AND HVAC, and CABLE TRAY!
Since MEP is in the Plant Suite now, you’ll also start seeing articles regarding it.
Stay tuned as we dig deeper into the new features and workflows for Plant 3D 2016!