Yes, light speed
The article you link to is on quantum communication- quantum communication in this case is accomplished by photons, which of course travel at the speed of light.
Entangled photons seem to "communicate" with each other instantaneously (collapse of one into a definite state immediately determines the state of the other, no matter the distance between them) but this fact cannot be used to transmit information from one place to another faster than the speed of light.