We have performed experiments to probe directly the thermal conductance of suspended nanostructures with lateral dimensions ~100nm. It has been recently predicted that at low temperatures, thermal conductance in such a structure approaches a universal value of for each massless, ballistic 1D channel, independent of material characteristics. We have developed ultra-sensitive, low dissipation dc-SQUID-based noise thermometry, and extreme isolation from the electronic environment in order to perform this measurement at temperatures <100mK. We will report our very recent successful measurements of this universal quantum of thermal conductance and the implications for single photon and possibly single phonon calorimetry.