The intrinsic transverse momentum of partons has been measured in di-hadron correlations induced by the approximately back-to-back correlations of outgoing partons in hard 2->2 partonic processes. We review experimental and theoretical aspects of extracting the k_T width from emerging data taken at RHIC. The obtained width is similar to the one used earlier to describe single-particle production at RHIC. Allowing a beam-energy dependence of the width of the k_T distribution provides a satisfactory description of spectra in pp collisions in fix-order pQCD calculations in a wide energy range. The nuclear effects required for pA and AA collisions are treated on this background. Our model incorporates isospin, shadowing, and the broadening of the intrinsic transverse momentum distribution due to multiple scattering. The model constructed along these lines successfully describes the Cronin effect at mid-rapidity, and provides a useful reference for calculations of jet energy loss.