Techniques and architecture are disclosed for providing a modular lighting system/luminaire having an integrated heat sink assembly. In some cases, the system/luminaire may comprise a plurality of individual modular light sources which have been operatively coupled with one another. In some instances, a modular light source may include one or more light engines (e.g., light emitting diodes or LEDs) which have been operatively coupled with an individual heat sink module. When assembled, the plurality of heat sink modules may define, in the aggregate, a plurality of heat conduits which dissipate thermal energy from the light engines by convective heat transfer. Also, in some cases, the heat sink modules may be electrically isolated from one another, allowing for the heat sink assembly itself, in part or in whole, to function as part of the desired circuit.