Spectrum regulation challenges grow for both unlicensed (e.g., Wi-Fi) and licensed (e.g., cellular) opportunities, particularly those created by 10's to 100's of billions of connected, communicating devices. Dynamic, cognitive solutions just begin to find field use and initiate the inevitable march towards increasingly artificially intelligent allocation of spectra and space. This talk reviews some multiuser fundamentals, their complexity of solution, and how they may find future application to magnify spectral efficiency by orders of magnitude.