The channel capacity of a multiple input multiple output (MIMO) system that uses a hybrid beamforming (HBF) mechanism for a 2×2 dual-polarized (DP) planar antenna array (PAA) is studied in this work for indoor 60 GHz channels. On one hand, the DP-PAA can resolve the receiving dead zone problem often seen in single-polarized PAA. On the other hand, the HBF architecture allows us to explore the advantages of spatial multiplexing or beamforming, or even both, in order to overcome the severe power loss problems often encountered from blocking or reflections in indoor 60 GHz radio propagations. Simulation results show that different architectures have advantages at different transmission power. In typical operating conditions of indoor 60 GHz radio, directivity offered by beamforming provides a higher capacity than does the spatial multiplexing provided by multiple baseband processing modules.