apache2-mpm-worker 2.2.16-4ubuntu2 (amd64 binary) in ubuntu natty

 Each Apache Multi-Processing Module provides a different "flavor" of
 web server binary, compiled with a different processing model.
 .
 The worker MPM provides the default threaded implementation. It is
 recommended especially for high-traffic sites because it is faster
 and has a smaller memory footprint than the traditional prefork MPM.