The build/release system is currently written in perl (v5.8.0) and should be reasonably cross-platform although it hasn't been tested on anything other than a MS-Windows development box. Please read the "_release.pl" file in the root directory of the source tree for more details.
Though I've entertained thoughts of writing a new set of build/release tools in CommonLisp, none of the BSD licensed CommonLisp implementations are ready for use on MS-Windows by mere mortals. The SBCL (Steel Bank Common Lisp) project has an on-going porting effort for the MS-Windows platform that was started in December 2005 and if the efforts continue, someday there will be an freely usable CommonLisp implementation.
The existing build/release system is not the most intuitive code ever written and it still needs to be properly documented. It uses ! delimited data files to decide what needs to be put into the "Release" archive and to generate the correct files needed by the Installer program.