  The polarization of the prompt $\gamma$-ray emission has been measured in
four bright gamma ray bursts (GRBs). It was nearly maximal in all cases, as
predicted by the Cannonball (CB) model of GRBs long before the observations.
These results are inconsistent with standard models of GRBs wherein the prompt
emission is due to synchrotron radiation. A much smaller linear polarization is
predicted by the CB model for the prompt emission in X-ray flashes (XRFs) and
in extremely luminous GRBs. These measurements would provide yet another
stringent test of the CB model and its unification of GRBs and XRFs.
