The Multiverse Client, on which the Firefly MMO will run, has been released. There’s an article on GigaOM portraying it as a competitor for Second Life (not quite accurate, that), and also the official press release. Games called Dark Horizons and Forgotten Legends have launched with it, and two called Force of Arms and LunarQuest are noted as “coming soon”. There’s no mention of Firefly in the Multiverse release, but it’s mentioned in the GigaOM article.