This reddit points to Rocket Lab's news page Rocket Lab successfully circularizes orbit with new Electron kick stage. It is named Curie, presumably after Marie?
According to the Rocket Lab's article:
The kick stage is designed for use on the Electron launch vehicle with a payload capacity of up to 150 kg and will be used to disperse CubeSat constellations faster and more accurately, enabling satellite data to be received and utilized sooner after launch.
Equipped with a precision pointing cold gas reaction control system, the kick stage also has its own avionics, power and communications systems.
It sounds a little bit like a rocket-propelled cubesat dispenser. Is that what it is? What sort of propulsion does it use?