Hydrophobic vs Hygrophobic. Rejection of water vs rejection of moisture/humidity. Also, something that is specifically hydrophobic may not behave similarly with oils. Personally I would love a low wear, high natural lubricity, hygrophobic coating... keeps the gun dry from water but not lubricant, takes bumps and dings well and doesn't wear off with heat and friction. Hydrophobic could be too extreme in my opinion, at least for internal parts... for an exterior coating it may be great as anything that is remotely water based retains its surface tension and literally slides off.
Grey Mana, I think what you are referring to is Hex-Boron-Nitride. It's a dry coating style lubricant like Teflon with good wear resistance and great lubricating properties... it's also extremely good at transferring heat, unlike teflon.