I did a talk last night at the London HTML5 Game Developer meetup. Seems like it went down pretty well. It was an overview of the ammo.js physics engine which is what we use internally for our physics.
Here are my slides: http://slid.es/davee/introduction-to-ammojs
Should be interesting for people who aren’t too familiar with what a physics engine is/does, and what sort of things you can do with the PlayCanvas physics.