It appears that update-alternatives is a very handy facility in Debian derivatives for keeping track of the preferred application for specific tasks.
This seems to be a much SAFER than Windows way of handling things (i.e., let the application try to set itself as the default handler–a la IE vs. Firefox, whatever audio player you use, etc…).
This also seems to be much cleaner than what I’ve experienced in the past with Linux–maybe trying to override one browser with another, creating a random soft link, etc…
All such alternatives can be seen in the /etc/alternatives directory. On a Kubuntu 6.10 (Edgy Eft) box, one finds among the alternatives java, pager, x-terminal-emulator, x-window-manager, and x-www-browser. Some alternatives are used to point to specific versions of a program.
The files which control the list of alternatives are in /var/lib/dpkg/alternatives.