  I review the recent progress in the theory of s-channel helicity
nonconservation (SCHNC) effects in diffractive DIS. SCHNC in diffractive vector
meson production is an unique probe of the spin-orbit coupling and Fermi motion
of quarks in vector mesons. Photo- and electroproduction of the $\phi$ and its
radial and angular excitations at Jlab is perfectly posed to probe SCHNC in QCD
pomeron exchange. I also discuss the unitarity driven demise of the
Burkhardt-Cottingham sum rule and large & scaling departure from the
Wandzura-Wilczek relation.
