  We consider a superexchange Hamiltonian, $H=-\sum_{<i,j>}(2{\bf S}_i\cdot
{\bf S}_j-\frac 12)(2{\bf T}_i\cdot {\bf T}_j-\frac 12)$, which describes
systems with orbital degeneracy and strong electron-phonon coupling in the
limit of large on-site repulsion. In an SU(4) Schwinger boson representation, a
reduced spin-orbital interaction is derived {\it exactly}, and a mean field
theory has been developed by introducing a symmetric valence bond pairing order
parameter. In one dimension, a spin-orbital liquid state with a finite gap is
obtained. On a two-dimensional square lattice a novel type of spin-orbital
ferromagnetically ordered state appears, while spin and orbital are
antiferromagnetic. Moreover, an important relation has been found, relating the
spin and orbital correlation functions to the combined spin-orbital ones.
