Baked into the terrain, huh. Is this something new? Didn't skins have to be approved by HTC for use online, originally (then they would be available for download by the community)?
No, the ability to replace the default skins in terrains has been around since AH2. It was usually only done in the cases of skins for substitute aircraft, but I've made it my mission to try to get as many location specific skins into their respective terrains. Thankfully, Greebo and Ghostdancer(from the official terrain team) have been willing to help in this endeavour.