Spherical 360 stitched cameras are becoming more and more common. It would be nice to have an option similar to the fisheye option to import these photos.
I admit, I've yet to try this with fisheye, but because of the innacuracies of the stitching, I can't see it working. It needs to have a sort of tolerance added to the areas of stitching. PHotoscan would need to know where these are and treat them differently or mask them.