2.4GHz is a completely different frequency, think of it as 2400MHz as apposed to your 72MHz (in the Americas) or 35MHz (in Europe).
this range of frequencies is commonly known as the ISM (Industrial, Scientific, Medical) band.

From what I've read, this will avoid channel conflicts in the future, I'm not sure how the Tx+Rx negotiate an actual frequency, or in the case where it might use frequency hopping (changing frequencies often to avoid interference), some sort of pairing may be used.
It will probably only work using PCM as it will be more advanced in signal detection.

To generate a 2.4GHz frequency is also a lot more power efficient, however the antenna's are a lot more specialised, from my own experience in the wireless world (Data Communication) using 2.4GHz for RC planes could limit range depending on the power output from the Tx (in Europe, the max allowed output is 1watt for 2.4GHz), other types of interference could be encountered too, any water which gets into the antenna will prove disasterous as water absorbs signals on this frequency (your microwave at home operates at 2.4GHz too!!)

I'm interested to see other people using 2.4GHz Tx+Rx's before I even think about trying it!!

RN