We write on the walls all the time (albeit on jumbo Post-It pads). It's a great way to freeflow ideas -- for designs, for campaigns, for new initiatives.
Because those 3' x 2' Post-It pads are portable, we've used them on client engagements both local and out of state. But for projects in the office, I'm thinking maybe all we need is a new paint job. With the stuff in this video.