|MadSci Network: Physics|
There are some speculative cosmological theories in which magnetic monopoles exist and play an important role. For this and other reasons, a group at Stanford U. has conducted a careful search for magnetic monopoles, without finding any. See M. E. Huber, B. Cabrera, M. A. Taber and R. D. Gardner, Physical Review D 44, 636 (1991). The construction you described is a sphere covered by a layer of magnetic dipoles. The magnetic field outside such an object (assuming it is perfectly spherical) is zero everywhere. The calculation is exactly the same as for a sphere covered by a layer of electric dipoles.
Try the links in the MadSci Library for more information on Physics.