apache2-mpm-itk (just mpm-itk for short) is an MPM (Multi-Processing Module)
for the Apache web server. mpm-itk allows you to run each of your vhost
under a separate uid and gid - in short, the scripts and configuration files
for one vhost no longer have to be readable for all the other vhosts.

WWW: http://mpm-itk.sesse.net/