Bocoup is hosting a Wikipedia editathon/hackathon from 10AM to 5PM on the 6th of April. On the edit side of things we'd love to focus on improving wikipedia's coverage of open web technologies (notable libraries, languages, design patterns, etc.) but we're happy to have anyone come and contribute on an article they're interested in improving. 

The hackathon side is completely open. We people to get excited about contributing to Wikimedia projects technically but we're also looking forward to see cool things get done to user scripts/styles, the API and data derived from Wikipedia. 

I'm going to add a page on Wikipedia proper soon enough. The details there should basically mirror those on Meetup.com. Please email me (or leave a note on my talk page) with any questions. 

Thanks,

-Adam