MDN Hack days are 1-day events comprising of morning lightning talks from Mozillians on Mozilla projects & open web technology, followed by an afternoon of hacking and collaboration. Participants should show up ready to write some include on their wifi-capable laptop, and hosts should be able to handle or appropriately direct questions from participants in order to enable the hacking.
March 24: MDN Hack Day NYC http://bit.ly/mdn-hackday-nyc
Sample schedule: