Not mine, and though I can't find a page on their site that states it, Vendetta Online[1] uses Erlang heavily for their server code. I went to a conference they spoke at a while back, they've said it works wonderfully for them and lets them handle large amounts of players easily.

They are also working to release a game engine (NAOS[2]) built from their server code, which also uses Erlang pretty heavily

[1]: http://www.vendetta-online.com/ [2]: http://www.guildsoftware.com/products.html