Last year, Hennessy et al. (Nature, v445, 896 (2007)) presented an experimental study of the puzzling quantum nature of a single semiconductor quantum dot strongly coupled to a planar photonic-crystal nanocavity. With the quantum dot strategically positioned close to an electromagnetic field antinode spatial position, optical measurements clearly observe the strong-coupling regime, giving rise to the familiar anti-crossing behavior that occurs between a single exciton and cavity mode. In addition to the usual cavity-QED regimes well known from atomic optics, Hennessy et al. highlighted several apparent mysteries, unique to the semiconductor environment. These effects include "off-resonant excitation of the cavity mode'' and a "triple peak'' during the strong coupling regime. This talk will try to explain these so-called mysteries (which have now been observed by a number of groups around the world) using a quantized medium-dependent theory, and then introduce some of our recent designs for realizing efficient quantum light sources on-chip.