BuildFactory v(1.0) has been released today, you can read more about it on its own product page. BuildFactory brings mass production (mass builds, rather), as well as continuous integration to the Mac platform. BuildFactory uses standard Xcode project files (.xcodeproj) and allows users to add any arbitrary amount of project files, or the same project file with different configuration settings, to the workspace, and build them all with the click of a button.
BuildFactory also integrates nicely with SubEthaEdit, TextMate, BBEdit, TextWrangler, and Xcode as external editors, allowing developers to quickly open up and fix any warnings or errors BuildFactory generates while building their projects. The demo version of BuildFactory limits you to four projects at a time, so download it and give it a try!