We've had a few MediaWiki talks at OSCON recently (this year Trevor and Roan did a great presentation about ResourceLoader); it tends to be a good mixer conference for the US FOSS community and has had great JavaScript and mobile tracks the last couple years (though it does have some vendor overload in other areas).
Just a heads-up that the call for presentations is due in January:
http://www.oscon.com/oscon2012/public/cfp/197?imm_mid=079f65&cmp=em-conf...
-- brion