Utilising the Geo positioning and accelerometers within the iPad, It should be possible to synchronise your 3D model view with the directional view of the iPad.
I work in the Process Plant Industry. To have a "Real-time" link back to the 3D Model (and associated meta data) of what you are actually looking at in the Plant would be of great value.
Some of you will respond with "Post this in the naviswork section ! " - My reply will be - There should only be ONE viewing tool for the whole of the Autodesk portfolio ! ( Oh, that might spark another discussion ! )