This emulates a feature in danga's perlbal. the ability to join multiple files together in a single request.

This is a performance optimization. instead of requesting 5 seperate CSS or javascript files from your server, you can do it one request.

If you must use something inferior to Apache2,

there is a lightptd version available here - http://code.google.com/p/lighttpd-mod-concat/

(just teasing guys!)