Rob,
Generally speaking...
The radio frequency 'band' that is used is the 2.4GHz ISM Band. It is a section of frequencies carved-out for use with unlicensed radio equipment like WiFi and is what is used in the Phantoms.
The 32 channel (hack) allowed the Phantom's system to be tuned to a bit above the carved-out frequencies into an area reserved for other licensed use.
Because these upper frequencies are not part of the un-licensed band they are frequently not in use and therefore there is less noise or competing signals making them more desirable cause you have better range and little to no noise issues.
Because it is technically illegal to use these frequencies it seems steps are being taken by some developers, etc. to make them no longer accessible through various changes.