In some of the HOWTO's:
"Apache2-SSL-PHP5-Howto (+Zend Optimizer And IonCube Loader)"
"Postfix-SMTP-AUTH-TLS-Howto" etc. programs are installed on a debian system by downloading the source files, building them and then installing them.
Why not use the debian packages? (apt-get install...)??
This is for showing how to compile things from sources, and these tutorials are meant for all distributions, not just Debian or Fedora or SuSE (you might have to adjust some paths, that differs from distribution to distribution, but the general direction is the same...), so there's no specific package manager to use.
If you want to know how to install these things with packages, have a look at the "The Perfect Setup" series here on HowtoForge, there are tutorials available for Debian, Fedora, Mandrake and SuSE.