For SCTA-BNI events, Speedweek, World Finals and El Mirage the HNR device is required for all new cars. A new car is one that has never turned a wheel in anger at a SCTA-BNI event. All other cars are required to begin use Jan 1, 2011.
That said, the USFRA, World of Speed, uses the SCTA rulebook so I think they will follow the same requirements. I do not have an official word from them yet.
DW