I'd like to invite you to the hackathon Wikimedia Foundation is putting on next month in San Francisco.
https://www.mediawiki.org/wiki/San_Francisco_Hackathon_January_2012
We're focusing on outreach for this one, teaching new developers how to build stuff using Gadgets and our web-accessible API and Phonegap. A bunch of WMF's San Francisco engineers will be there, plus (we're planning) Derk-Jan Hartman, Maarten Dammers, Daniel Kinzler, and a few more experts from out of town. Whatever your level of expertise, we welcome you, as a learner and as a hacker.
Please spread the word and please consider coming. Thanks!