Our friend [Rich Mogull] has been flipping the switches on Leopard’s new firewall and scanning it to see what’s actually going on. There is some good and some bad. The new application signing is a mixed bag. It breaks Skype and a commenter pointed out that automatically trusting Apple installed apps like NetCat isn’t a good idea either. You can roll your own firewall using user friendly tools like WaterRoof since ipfw is still included.