Ross Tuck gave a one of kind closing keynote at this year's (excellent) Dutch PHP Conference. Clear your schedule for the coming hour and watch the video of the talk with full attention. It's really great.
At the conference there were a lot of talks on events sourcing. The two talks with that subject that stood out for me were Shawn McCool's (where he applied event sourcing to the board game Quantum), and Greg Young's opening keynote. Watch the latter one here: