It's gonna be i3detroit's first year hosting a Software Freedom Day event and we're not quite solid on what to do. We're a pretty hardware-centric group, so it looks like some open platforms (beaglebone, at least) might be the focus.
I'm curious what other folks are doing, what's worked well in the past, how you get the word out, any pitfalls to avoid, etc. 
Also thinking about firing up our ustream and trying to get it connected to the synchronous hackathon page... that'll depend on how much free time we have ;)
-Nate B-