GRL and Eyebeam have posted a new instructable on portable projection, with advice on projector output, projection surfaces, car and battery selection, and how not best to overload your inverter, causing it to shoot flame inside your rental van.

Outdoor digital projection in urban environments is a great method for getting your content up big before the eyes and in the minds of your fellow city inhabitants. This tutorial comes out of trial and error and it works. But please be careful. Helpful comments on safety and alternative methods are encouraged. The majority of this tutorial is aimed toward using a 2500 lumen projector (or smaller)