What are 10/20's?
The day is all about great conversations with a small groups of your new friends. Each block will have a moderator or group leader, made up of the speakers and other people we've invited to help spur conversation and make sure things are kicking ass.
The blocks are open for anyone to start/lead/contribute to a discussion about an idea you want to share or tackle as a group. A business challenge you have, a new technique or even to demo something you've built.
You can prepare topics beforehand or you can show up and contribute ad hoc. Planning isn't as important as your willingness to share during the day. So be open and share and you'll get an immeasurable experience out of this.