I did a little interview on Late Night Cocoa, where I talk about source control, build scripts, and a bit of automated testing.
I also referred to an example project that I'd be providing, showing how to do the automated build stuff. You can check it out using subversion:
svn checkout http://flycode.googlecode.com/svn/trunk/buildapp/ buildapp
It checks out the project, builds it, copies it to a custom disk image, archives the build, and it even includes a line showing how to update twitter with "hey, I just made a new build!"
Or... for extra geek points, just paste this in the terminal:
But of course, you'll want to review the build script first to see what is going on (it creates a new folder in your home directory as well).