... well, firstly, nobody has ever said "welcome" to me ... at least not that I'm aware of ...
... secondly it's blooming scary trying to get involved in brainstorming, bugzilla, voting for suggestions, testing etc ... I don't think it's really a question of literally welcoming newbies (although that certainly doesn't hurt!) ... for me it's more a kind of bridging that's needed to ease me and other newbies into becoming a productive member of the community ...