Here are a few notes I've made on keeping the the screen from blanking in linux. I generally am using Ratpoison (and sometimes just the console), so these are notes on how to disable screen blanking in X and console situations, not the higher-level GNOME or KDE screensaver. I've come up with a configuration that works to keep my screen from ever turning off, but I don't have an in-depth understanding of exactly what's being done. Some of this may be redundant.
I'm going to explain how I auto-start ratpoison on my bare-bones Debian Stable (Lenny) system. I don't use GDM, KDM, or any other "DM" (display manager). There are multiple steps here (involving multiple config files), but it is not complicated.
/etc/inittab & mingetty
mingetty is an alternative to getty, which (for the sake of simplicity) I describe as the linux login program. You'll need to install mingetty:
#as root (i.e., using either su or sudo) apt-get install mingetty