I guess I haven’t been keeping up. I knew it was authorized, but not that it was in common use.
Yeah, it took the R/C world by storm. Long gone are the days of frequency flags and 'shoot-downs' due to someone turning on a radio on the same frequency.
All the major radio manufacturers (Futaba, Airtronics, JR, Spektrum, etc.) have been selling hobby-grade 2.4Ghz radio systems for over 10 years. In fact, these days you'd be hard-pressed to find an FM or AM system available for sale at the retail level.