Getting random people together to get (possibly even more random!) projects done is great. I’m not a developer so I wouldn’t go, but I love it when I see people doing things like this. Go go go!
But why would you have everyone spend their time in committee meetings all day, and have to switch focus halfway through? It’s only one day, it’s not like they’re stuck in a rut. In other words, what does breaking everyone’s concentration accomplish?
If I were planning my own version, I’d do something like this:
1. Announce it a few weeks ahead, set a date
2. Ask potential attendees (no set number, there’ll be some attrition) to post ideas of what they want to get done online, using a specific tag so everyone can search each other’s posts
3. Hold a meet up one evening a couple days before, for everyone who wants to attend to meet and figure out which ideas to work on and who wants to do what
4. Let everybody stick those ideas in the back of their heads for a couple days and start the creative juices flowing
5. Show up, caffeinate, get shit done
But then I guess it wouldn’t be much of a mashup, would it? Maybe I’m just too comfortable with the blinders on/not ADD enough to see the appeal.