Ahh Fenrir, Akasha has been around since, like, the Beginning of the Game. Check the Old (and I mean OLD) AL's she's in some of the Early chapters. She was just absent for a rather long time.
Still Some of the RPCs that are on the list are relatively new, I've been around about a year myself and there are some RPCs who joined after me.
Edit: And to Watcher, Actually the Order of the list doesn't really have to do with Age, or Length of RPC service.... In Fact I have no Clue what the Order represents. However you are right that Akasha is an Ancient player.