The nearest thing I have seen to this is sculpty's in Second Life you can create a (sort of) normal map from a 3d object in your modeling program (I know your asking if its possible to create an object from a normal map but where do you get a 3d normal map in the first place?) and it is applied to a sculpty object.
There is a tab for changing basic primiitive objects such as a cube to sculpty in object properties, you then have a basic sphere,box,plane or torus sculpt object and when the sculpty map is applied, it will transform into a very basic model (this is due to prim objects having a limit of 1024 faces). The detail is in the texture but it still looks great.
I have made many models this way in the past and still occasionally dabble in it to keep my hand in,if you break it up and add more than one sculpt together you can create some fairly convincing objects.
Heres an example of a single object sculpt map:
This is an example of an eleven prim sculpty model (the screenshot was taken in Second Life):
The legs, arms, pants, head etc are all single sculpted prims.
I have no idea how this works in the engine (I only know how to create the sculpts) but I believe Second Life is now open scource so maybe one of the more savvy folks around here could give you a more definitive answer.
I have tried applying straightforward normal maps to sculpty's but it doesnt work that way, the scuplt normal maps have to be created from objects that have either 1024,2048 or 4096 faces(whatever res you use the scuplt prim will still only have 1024 faces) with a flat planar mapping.
Awesome! Its one of those threads.
