Maybe not a good thing for it to be actually officially designated. They tried that on the oldguild, made people "comrades" who's specific job was to greet new users. People got butthurt over it, majorly butthurt.
But I don't see why we couldn't do one on the side, no rank involved. Set up a couple of group PMs. Or we could just do it like we've been doing, kind of everyone chip in every now and again and just have a chaos of welcomes. It's more friendly that way; I know on the oldguild it often was reduced to a copy/pasted message by one comrade or another. It's so much more personal this way.