Review of recent results from RHIC on the polarized gluon distribution

RHIC provides a unique laboratory to study the spin structure of the proton, using strongly interacting probes. Through remarkable control of the proton acceleration process, RHIC has achieved collisions with 55 to 60\% polarized proton beams, at root(s)=200 GeV, with high luminosity. Two experiments, PHENIX and STAR, feature measurements of inclusive production of jets, jet fragmentation products (with emphasis on pi$^0$), and direct photons, which probe the gluon polarization in the polarized protons. I will discuss how we connect the measurements to the underlying physics and the present (sensitive) and future constraints on the gluon spin contribution from RHIC.